Performance beast! Asus Zenfone 2 Review

Our Rating

Battery Life7.5

It is an relatively easy task to enter the smartphone market, but it isn’t as simple to gain the heart and attention from all the consumers around the world. However, Asus has did it once again during the Asus Zen Day on the 9 of May 2015. This time, Asus has brought the world most powerful and latest Zenfone into the Southeast Asian market. One of the most welcomed specification is the device is one of the world first smartphone that carries 4GB of RAM! Named as performance beast, how much performance does Zenfone 2 provides? Check out our in depth review of this smartphone!

Asus ZenFone 2 ZE551ML (Premium) specification

  • Android 5.0 OS(ZenUI 2.0)
  • 5.5′ 1080p Full HD IPS display(403ppi)
  • Corning Gorilla Glass 3 scratch resistant glass
  • 2.3GHz 64-bit Intel Atom Z3580 quad core processor
  • 533MHz PowerVR G6430 graphic processor
  • 64-bit dual band 4GB RAM + 64GB internal storage
  •  supports up to 64GB Micro SD storage expansion
  • 13MP rear camera + 5MP front camera
  • Dual SIM standby (only SIM 1 supports mobile data connection)
  • Bluetooth 4.0 transfer technology
  • supports NFC
  • non removable 3000mAh battery
  • 152.5 x 77.2 x 10.9mm
  • 170g

Asus Zenfone 2 variants:-

ZenFone 2 ZE500CL

~5寸HD display、1.6GHz Intel Atom Z2560、2GB RAM、8GB ROM(RM599)

ZenFone 2 ZE550ML

~ 5.5寸HD display、1.8GHz的Intel Atom Z3560、2GB RAM、16GB ROM(RM749)

ZenFone 2 ZE551ML

~5.5寸FHD display、1.8GHz的Intel Atom Z3560、2GB RAM、32GB ROM(RM899)

~ 5.5寸HD display、2.3GHz的Intel Atom Z3580、4GB RAM、32GB ROM(RM1099)

~5.5寸HD display、2.3GHz的Intel Atom Z3580、4GB RAM、64GB ROM(RM1299)


2. Design story

The Zenfone 2 still comes with the conventional design that was saw in the first generation of Zenfone 4, 5, 6. The front part of the smartphone appears separated into 3 parts where the top and the bottom part were crafted with a reflective metallic design. However, the size on the top and the bottom metallic part has largely reduced which appears more fit in today trendy smartphone design. The screen takes up 72% of the whole body which makes the viewing experience fascinating!

In the bottom part of most android smartphone lays the 3 most essential navigation switch – back, home and recent menu button. Zenfone 2 also carries the same button layout with the back button located on the left side of the phone. Unfortunately, the Zenfone 2 does not carries the notification LED light but the still maintain the concentric circle design on this smartphone which makes the light reflection from every angle looks awesome!.

the big ASUS logo was printed on the top of smartphone beneath the speaker grill besides the 5MP front camera with F/2.0 and 85 degree wide angle lens!

One of the non-ideal point of this smartphone is the power button was translocated into the top of the device. Operating in a single handed operation will be very inconvenient when the power button is required to unlock the screen. However, Asus solve this issue with Double Tap features which instantly wake the device when screen is double tapped. Nevertheless, apart from the power button, the 3.5mm audio jack is also located at the top along with a microphone!

The microUSB/ charging port of the Zenfone 2 is located in the bottom. It supports Asus Boostmaster technology quick charge technology which we will further test it on later. A noise cancellation microphone is also located at the side.

Zenfone 2 comes with a curved back polycarbonate cover with a brushed metallic design. However, we felt that the polycarbonate back cover gave a mushy plasticky feeling which drags down the premium design of this smartphone.

One of the greatest concern of the Zenfone 2 is the contamination of lens with the fingerprint when searching for the volume rocker. However, Asus makes the whole volume rocker appears oval and rectangle which users can instantly felt it when holding the phone in a single hand. However, we do think that the volume rocker is a non-so frequent key to be use in daily operation.

Although the Zenfone 2 features the a body long speaker grill on the back, the main speaker is located onto the left side of the smartphone, thus there is no stereo audio for this device! Nevertheless, this smartphone supports Asus SonicMaster audio technology that enhance the audio quality but not its volume.


2. Display

Zenfone 2 carries a FHD 1080p IPS display with pixel density up to 403ppi. Although 1080p display is no comparison to other 2k display smartphone, full HD IPS on this Zenfone 2 is pretty sufficient (and battery saving!). Sporting Corning Gorilla Glass 3, the display offer slight scratch resistant functionality (but we dont dare to put it onto test!). The screen also takes up 72% of the front body which is considered as pretty large compared to some other smartphone out there.

Zenfone comes with one of the largest viewing angle from some other smartphone other there. The 140 degree wide view angle gives you ability to share the display when watching videos together! The luminescence are great when the device is place right on top of the table and the picture still able to retain its image quality which give another big boost to this display.

One of the downside of this display is the luminescence of the display under bright environment. Although the Asus Zenfone 2 comes with impressive display, the low luminescence of the display is still a big downpoint of this device. It is advisable to adjust the brightness to 70% (or adjust it to auto-brightness) so the display is still visible under sunlight.

There is no color leak issue reproduced in the Zenfone 2. Even with the brightness is adjusted to the maximum, no serious display issue was observed as the color remains well balance and well saturated. Prolonged viewing does not cause eye strain (but we strongly do not encourage viewing or staring the display for a long period of time).

Ahh, the only pain of the display. You might even need to adjust the brightness to maximum to get things done under bright sky!

We compared the display of the Zenfone with Xiaomi Mi 4i and HTC Desire 826. Although all 3 models were known to use 1080p display, the 5 inch Mi 4i display has a stronger color density due to high pixel density. Although the Zenfone 2 and Desire 826 features 5.5 inches display, the Zenfone 2 has a better display when it comes to detail reproduction. +1 for Zenfone 2!


3. Camera

Although the 13MP camera with F/2.0 aperture could be a norm for all the flagship smartphone out there, the PixelMaster 2.0 technology from Asus has bring photography to another new level! If you has been noticing all those photo up there, you might notice that there is a dual LED flashlight on top of the camera! The dual LED flash serves an important key in producing image in dark environment more surreal by mimicking natural light.

PixelMaster 2.0

A tiny change of the PixelMaster can be observed in this Zenfone upgrade. Apart from the mutli mode selection that gaves the user more option to take the ideal photo, the Zenfone 2 upgrade also comes with manual mode and the super resolution mode which takes pictures and combine them up to 52MP!

Manual mode

The Manual mode in Zenfone 2 offers adjustment of exposure value (EV), ISO, White balance, focus distance and shutter speed. However, the shutter speed option is fairly limited as it can be only adjusted to half second only!


Super Resolution mode

The Super Resolution mode combines several image taken from the same area into a highly detail picture. Viewing from scratch does not provides as much impression compared to stock photos but there is a big room of difference when the image were zoomed in. This mode can capture and combine image up to 8192×6144 pixels!

Color optimization test

All the colours are appears natural. Looks like Asus has put in effort in the color reproduction of the camera!

Daylight shooting

In bright environment, the 13MP camera on the rear does capture and retain as much as details possible in the image. The photo quality of these bright shooting can even compete with 16MP flagship out there!


Night shooting

With the F/2.0 large aperture, taking image in the dark without a flash could be an easy task for the Asus Zenfone 2. The Low Light mode in the Pixel Master technology also provides optimization in low light shooting. Although there is some presence of background noise in the image, the noise volume still does not greatly affect the entire image quality when viewing from scratch. Another +1 for the Zenfone 2.

Indoor shooting

The picture quality in indoor shooting is only moderately acceptable. The whole picture appears waxy which greatly disappointing to us as some detail were lost significantly.

Food imagery

Those image seems undergone less post processing as much details were preserved (notice the amount of detail in the chrysanthemum flower). We found that turning on HDR mode boost the image quality even further.


HDR Mode

HDR shooting mode has greatly optimize the sunlight exposure in those photo settings. However, it is not the best that we seen.

Low light mode

Before low light

After low light


More sample pictures


Selfie testing

Apart from the satisfying image quality taken from the 13MP rear camera, the 5MP selfie camera also comes with lots of shooting mode which includes HDR! The camera is equipped with F/2.0 aperture along with 85 degree wide angle lens and able to capture every single facial expression in the dark!

There are tons of selfie facial auto-beautification settings.



HDR selfie


Wide angle selfie test

Our point of view: The whole camera performance on the Zenfone 2 performs average compared to other smartphone within this level. Although Zenfone 2 is equipped with zero-shutter lag, the picture and video quality still does not able to outsmart sample photos taken with OIS-capable camera. However, there will be much convenience in holding the smartphone in landscape position without the worry of pressing any hardware keys during shooting.

4. Software and OS

As the flagship of the Zenfone series, the Asus Zenfone 2 is equipped with the state of the art Android Lollipop operating system! The Zen UI has has a makeover which now comes with new applications such as Data transfer, Photo collage, kids mode and Zen Motion! Asus also collaborate with Trend Micro Security to provide the latest end to end protect against virus and malware on smartphone.

There isnt any much changes on the lock screen. However the black hole lock screen effect is pretty fascinating!

The Zenfone 2 still retains the traditional zenfone icons and the simplistic feel. However, most icon appears flatter which suits on the iconic Material Design of the Android Lollipop.

Swiping down first will loads the notification bar and further swiping down will launch the quick settings where you can toggle instantly without entering the settings menu interface.

Swiping up from the bottom in the home screen of the Zenfone 2 will launch more customization menu “Manage Home” which allows you to change your font size, icon label color, adding widgets, changing wallpaper and more!

The smart group function automated sort the application based on its category and classified by folder. It is easy and blazingly fast and uniform!

In the application menu screen, swiping bidirectionally with 2 fingers can automatically resize the amount of application icon present in the screen. The most compact sized application arrangement can be sorted with 5×5 as the maximum and 3×3 as the minimum as shown in the pictures above.


ZenUI 2.0 quick glance

Auto-start manager

By controlling which application to be launched during each boot, we found it greatly shorten the boot up time and lengthen the amount of battery life. The “Boost” function switch off background (non-essential) application which conserves you more memory for other application multitasking.


Do it later

Simply shaking your phone in both direction, you can save the moment which requires attention at a later period. This handy app allows you to record down important moments and things to do later which you can recap after you completed your mission in hand. However, the gyroscope in the Zenfone 2 could be too sensitive at some time so it cause unnecessary “saves” on Do It Later app.



As the name stated, this application gives you choice and more freedom in editing photos! The PhotoEffects also comes along with several template such as Color Lab、Whirpool、Little Planet and Worm Hole.


The ZenUI 2.0 also gives user a choice to change their home theme. However, there are only 7 available theme ready to pick from this app. Hopefully more option and themes will come soon!

Clean Master

The clean master is a stock application pre-installed into the system before marketed out. This application cleans your files and folders as well as free some RAM (as what the “Boosts” does). Users can also get to know which application is haggling their battery the most with this application. Although it does its job in providing information to the end user in terms of storage and application management, we found that this app is likely a junk for those geeky droid users out there.

Dr. Safety

Since our world is surrounding is unseen threat, an antivirus in a smartphone could be essential in protecting you against malware. However, prevention is better than treatment!


Another instagram platform for Zenfone 2 users?








Who doesn’t concern of their privacy? the SnapView in Zenfone 2 protects your files from exposing from stranger which is similar from KNOX from Samsung.



The Touch Gesture is an essential application to launch any application when the smartphone is on standby mode. Since the power button is located on the of the device which makes it inconvenience to press during single handed operation, Asus has added in the Double Tap to wake feature which makes it much more easier to turn on the display. However, this function seems to be alittle bit over sensitive especially when the phone was placed inside a pocket. 

One Hand Mode allows you to resize your display if you found it too large to operate. This is very handy during single handed operation as some portion of the display is not reachable with hand. This function can be activity with a double tap on the home button.


5. Battery Life

Asus Zenfone 2 comes with a 3000mAh non removable battery. Although this capacity belongs to average in a 5.5 inches display, our initial prediction of the battery life of this smartphone should last as long as 2 days in fair use and 1 day in intensive CPU usage. Let’s put the battery into test!

Battery endurance test:-

  • 1/2 hr waze & data:10%
  • 1/2 hr FB + data:7%
  • 1/2 hr FB + WiFi:5%
  • 1/2 hr browser + wifi:6%
  • 1/2 hr game + wifi:22%
  • 1/2 hr youtube:10%
  • 1/2 hr whatsapp+wechat+camera+wifi:11%
  • 1/2 hr music:4%
  • 1/2 hr video playback:10%(1/2 hr with earphone)10%(1/2 hr with speaker)

The battery life of the Zenfone 2 was not as good as expect but perform pretty much the average! However, the Asus BoostMaster technology bring us some surprise! We tested out the claim that the Zenfone 2 is able to charged 60% for 39 minutes. Although it is not all the time that 39 minutes charge has recharged up to 60%, most of the time the experiments returns similar results. During the quick charge process, the Zenfone smartphone could appears pretty hot. If you experience as intensive heating or increasing temperature during charge, please consult Asus service center.


6. Performance

The Zenfone 2 is equipped with 64 bit Intel Atom Z3580 quad core processor clocked at 2.3Ghz. This processor is a major markup in terms of performance compared to older Zenfone models. The Power VR6430 graphical processor also able to does it jobs well in live rendering and the 4GB DDR3 RAM makes multitasking no longer an issue.

Antutu Benchmark Test

The Antutu benchmark score is undeniably impressive for a smartphone powered by Intel processor.

GeekBench 3

Epic Citadel

During our test, the framerate on the Epic Citadel benchmark can reach up to 100 fps and above! This result is pretty impressive and credits to the powerful Power VR6430 graphical processor. Thus, running games at high frame rate should not be an issue!

4K video playback

Honestly, we didnt expect that the Zenfone 2 can play a 4K sample video as smooth as observed on some other higher end smartphone models. It is slightly unfortunate that the Zenfone 2 does not equipped with a 2K display or above, otherwise it could be an impressive job!

Gaming test

Although we does not has a big hope on the Intel processor due to the previous report compatibility issue, our game test of Asphalt 8, Dungeon Hunter, Gangstar vegas 4 and Fifa 15 turns out fine! The gameplay is highly enjoyable and no compatibility issue were faced during our tests.

Internet browsing

The LTE Cat 4 internet connectivity once again add another great plus onto this device. The LTE Cat 4 supports connection speed up to 250 Mbps! Besides, the pre-installed stock browser does a good job in loading websites with different layouts.

RAM test

In this RAM stress test, we opened up to 50 different applications which includes games such as tower of saviors, gangstar vegas 4, YouTube, Waze and others. Turns out there was no lag observed even when 50 application was opened and 0.9GB of RAM left! All of the the background application can be launched almost instantly with the quick recent menu keys. Well done Asus



In short, Asus Zenfone 2 is a smartphone that comes with some minor changes in design factor but there is large improvements in terms of processor performance and multitasking. Although the camera takes great picture during daylight and photo imagery, there are some room for improvements in picture quality taken in dark environment. The selfie HDR is also a pretty innovative features that grabs your facial expression even in bright day light! This time, we’re not dissapointed with the compatibility issue previously reported on the first generation of the Asus Zenfone. Besides, we’re surprised by the amount of task that 4GB RAM performance beast can do!