Asus Zenfone 2 review: A balancing act

5.5-inch FullHD IPS panel

A 5.5-inch display adorns the front of the Zenfone 2. It utilizes an IPS panel of 1080p resolution which results in 403ppi, well above what's considered a Retina-grade 300ppi. Indeed, the display is sharp enough not to let you distinguish individual pixels and text is crisp even at very tiny sizes. The viewing angles are good, and despite the noticeable brightness and contrast fallout when viewed sideways, the screen remains clearly legible.

The screen is covered in Gorilla Glass 3 for scratch and shatter resistance. It's very prone to smudges though and care must be taken to keep it clean. There is a dedicated glove mode for increased touch sensitivity at the expense of slightly shorter battery life.

Asus has the Splendid app, which lets you adjust your screen color profile. The default setting out of the box is Vivid, which produces pleasing colors with plenty of punch. However, if the Vivid setting is too much for your taste, you can opt for a more subdued Balance mode and both have a slider for color temperature adjustment.

Reading mode brings the saturation further down and provides another slider, which gives whites a progressively yellowish tint, to make it easier on your eyes in long research sessions. Finally, a Customized mode lets you adjust both hue and saturation separately.

Zenfone 2 display settings

Our microscope revealed a standard RGB matrix with an equal number of subpixels for all three colors.

The Zenfone 2 didn't impress with brightness and at the maximum setting posted only average results. The high black value also means a less than stellar contrast. At the 50% setting the display is actually closer to a quarter of maximum brightness and is in fact quite dim. Contrast deteriorates further as well.

The smartphone did manage an average sunlight legibility ratio despite its low maximum brightness. In reality, while you'll be able to discern what's shown on the screen, you're better off finding a shade.

Sunlight contrast ratio

• Nokia 808 PureView
  4.698
• Samsung Galaxy A3
  4.241
• Samsung Galaxy S6
  4.124
• Samsung Galaxy Note 4
  4.033
• Samsung Galaxy Note 3
  3.997
• Apple iPhone 5
  3.997
• Samsung Galaxy A5
  3.895
• Apple iPhone 6
  3.838
• Motorola Moto X (2014)
  3.816
• Samsung Galaxy Note Edge
  3.799
• Samsung Galaxy A7
  3.679
• Oppo R5
  3.678
• Samsung Galaxy K zoom
  3.675
• Nokia Lumia 930
  3.567
• Apple iPhone 5s
  3.565
• Samsung Galaxy S5
  3.549
• Nokia Lumia 735
  3.547
• Motorola Nexus 6
  3.543
• Alcatel Idol X+
  3.527
• Apple iPhone 5c
  3.512
• Samsung Galaxy Alpha
  3.509
• Samsung Galaxy Note 3 Neo
  3.487
• LG G Flex2
  3.465
• YotaPhone 2
  3.453
• Motorola RAZR MAXX
  3.42
• Samsung I9300 Galaxy S III
  3.419
• Samsung Galaxy S5 Active
  3.406
• Nokia Lumia 925
  3.402
• Gionee Elife S5.5
  3.386
• Samsung I9505 Galaxy S4
  3.352
• Samsung Omnia W
  3.301
• Samsung Galaxy S5 mini
  3.174
• Samsung I9000 Galaxy S
  3.155
• Samsung Ativ S
  3.129
• Samsung I9190 Galaxy S4 mini
  3.127
• Samsung Galaxy S4 zoom
  3.118
• Nokia N9
  3.069
• Apple iPhone 6 Plus
  3.023
• Samsung Galaxy Note
  2.97
• Samsung Galaxy Premier
  2.958
• Sony Xperia Z1
  2.95
• HTC One S
  2.901
• Lenovo S90 Sisley
  2.892
• Samsung I8730 Galaxy Express
  2.861
• BlackBerry Q10
  2.856
• Samsung I9100 Galaxy S II
  2.832
• HTC Desire Eye
  2.815
• Gionee Elife S5.1
  2.812
• Samsung Galaxy S II Plus
  2.801
• BlackBerry Z30
  2.79
• Meizu MX4 Pro
  2.765
• Sony Xperia ZR
  2.672
• Huawei Ascend P1
  2.655
• Sony Xperia Z3
  2.618
• Sony Xperia Z3 Compact
  2.616
• Sony Xperia T3
  2.609
• BlackBerry Passport
  2.595
• Nokia Lumia 900
  2.562
• Motorola Moto G 4G
  2.546
• HTC One Max
  2.537
• Nokia Lumia 720
  2.512
• HTC One
  2.504
• Motorola Moto G
  2.477
• vivo Xshot
  2.465
• Sony Xperia Z
  2.462
• Xiaomi Mi 4
  2.424
• Samsung Galaxy S III mini
  2.422
• Lenovo Vibe Z2 Pro
  2.416
• LG G Flex
  2.407
• HTC Desire 820
  2.372
• HTC One (M8)
  2.371
• Meizu MX4
  2.366
• Motorola RAZR i
  2.366
• Meizu m1 note
  2.362
• Sony Xperia ZL
  2.352
• HTC One M9
  2.334
• HTC One (M8) for Windows
  2.291
• Oppo Find 7a
  2.279
• Alcatel One Touch Hero
  2.272
• Apple iPhone 4S
  2.269
• HTC Desire 600 dual sim
  2.262
• Nokia Asha 311
  2.25
• Xiaomi Mi Note
  2.234
• Motorola Moto G (2014)
  2.233
• LG Nexus 5
  2.228
• Nokia Lumia 820
  2.193
• HTC One (E8)
  2.185
• Oppo N3
  2.181
• Nokia Lumia 920
  2.17
• Huawei Honor 6
  2.169
• HTC One X
  2.158
• Asus Zenfone 2 ZE551ML
  2.149
• Nokia N8
  2.144
• Nokia Lumia 620
  2.142
• Nokia 515
  2.134
• Archos 50 Diamond
  2.134
• HTC Desire 500
  2.129
• Sony Xperia C3 Dual
  2.12
• Sony Xperia acro S
  2.119
• Xiaomi Redmi Note
  2.119
• Nokia Lumia 1020
  2.103
• Oppo Find 5
  2.088
• Sony Xperia SL
  2.078
• Nokia Lumia 630
  2.056
• BlackBerry Z10
  2.051
• Huawei Ascend Mate7
  2.024
• Samsung I9295 Galaxy S4 Active
  2.022
• Apple iPhone 4
  2.016
• HTC One mini
  2.003
• Xiaomi Mi 3
  2.001
• Huawei Ascend P7
  1.992
• LG G2
  1.976
• OnePlus One
  1.961
• Oppo R819
  1.957
• Sony Ericsson Xperia ray
  1.955
• Lenovo Vibe X2
  1.952
• Sony Xperia Z2
  1.944
• Sony Xperia E3
  1.943
• Nokia Lumia 1320
  1.941
• HTC One mini 2
  1.94
• Samsung Galaxy Camera
  1.938
• Samsung Galaxy Grand Prime
  1.935
• Sony Xperia J
  1.932
• Acer CloudMobile S500
  1.931
• ZTE Blade S6
  1.927
• LG Nexus 4
  1.926
• LG G Pro 2
  1.922
• Samsung Galaxy Mega 6.3
  1.913
• Nokia Asha 308
  1.911
• HTC Butterfly 2
  1.905
• Sony Xperia T
  1.894
• Nokia Lumia 830
  1.887
• HTC Desire X
  1.878
• HTC Butterfly
  1.873
• HTC Windows Phone 8X
  1.873
• HTC Butterfly S
  1.867
• Huawei Ascend P6
  1.865
• Huawei Ascend Mate
  1.845
• LG G2 mini
  1.838
• LG G3
  1.82
• Nokia Lumia 1520
  1.813
• HTC Desire 616 dual sim
  1.797
• Sony Xperia V
  1.792
• HTC Desire 816
  1.783
• Sony Xperia Z1 Compact
  1.772
• HTC Desire 700 dual sim
  1.769
• Sony Xperia U
  1.758
• Meizu MX3
  1.754
• LG Optimus G
  1.753
• Sony Xperia T2 Ultra
  1.74
• Sony Xperia Z3 Tablet Compact
  1.735
• Acer Liquid Jade S
  1.734
• Sony Xperia SP
  1.733
• LG Optimus 4X HD
  1.691
• Oppo Find 7
  1.691
• HTC One V
  1.685
• BlackBerry Q5
  1.682
• LG Optimus Vu
  1.68
• Xiaomi Mi Pad 7.9
  1.672
• LG Optimus GJ
  1.666
• LG Optimus 3D Max
  1.658
• HTC Desire V
  1.646
• Samsung Galaxy Xcover 2
  1.632
• Samsung Galaxy Ace 3
  1.622
• Jolla Jolla
  1.605
• Sony Xperia Z Ultra
  1.578
• Sony Xperia go
  1.577
• Samsung Galaxy Ace 2 I8160
  1.566
• Samsung Galaxy Core
  1.563
• LG Optimus G Pro
  1.552
• Motorola Moto E
  1.545
• LG Optimus 3D
  1.542
• Nokia Asha 302
  1.537
• Samsung Galaxy Core Prime
  1.507
• BlackBerry Curve 9320
  1.488
• Sony Xperia M
  1.473
• Oppo N1
  1.47
• Sony Xperia E4
  1.467
• Meizu MX 4-core
  1.462
• Nokia Lumia 610
  1.432
• Samsung Galaxy S Duos
  1.4
• Microsoft Lumia 535
  1.393
• Samsung Galaxy Grand Neo
  1.393
• Sony Xperia M2
  1.393
• Samsung Galaxy Grand 2
  1.38
• Sony Xperia E1
  1.372
• Nokia Lumia 625
  1.371
• Gigabyte GSmart G1355
  1.361
• Sony Xperia L
  1.351
• Samsung Galaxy Mega 5.8
  1.35
• Xiaomi Redmi 1S
  1.35
• HTC Desire 510
  1.34
• Sony Xperia M2 Aqua
  1.331
• Sony Xperia miro
  1.324
• Samsung I9082 Galaxy Grand
  1.321
• Samsung I8530 Galaxy Beam
  1.315
• Xiaomi Redmi 2
  1.311
• HTC Desire C
  1.3
• Nokia X
  1.291
• Sony Xperia C
  1.283
• Nokia Asha 503
  1.281
• Nokia Asha 501
  1.27
• LG Optimus L7
  1.269
• Nokia Lumia 510
  1.268
• Samsung Galaxy Fame
  1.245
• LG Optimus L9
  1.227
• Meizu MX
  1.221
• Samsung Galaxy Young
  1.22
• Sony Xperia E
  1.215
• Nokia XL
  1.204
• Sony Xperia E dual
  1.203
• Asus Memo Pad 7 ME176C
  1.198
• Samsung Galaxy Pocket
  1.18
• Nokia Asha 305
  1.178
• Nokia Asha 306
  1.175
• Sony Xperia neo L
  1.169
• Sony Xperia tipo
  1.166
• Nokia Lumia 520
  1.161
• Samsung S6802 Galaxy Ace Duos
  1.148
• Samsung Galaxy mini 2
  1.114

Battery life test

The Zenfone 2 ZE551ML is equipped with a 3,000mAh battery, which is sadly not user-replaceable despite the back being removable. This sort of capacity is about average for a 5.5-inch smartphone.

While the scorecards below omit the standby times, our procedure includes measuring those as well and they are calculated in the overall rating. Our tests revealed that the Zenfone 2 can last as much as 10 days in standby when a single SIM card is used, which drops to about 8 and a half days when you pop in a second SIM. Voice calls will drain your battery in a bit under 16 hours which a respectable achievement as well.

Video playback longevity is nothing special but at 8 and a half hours it's adequate. What's more troubling is the browser department where the Asus Browser was nearly twice as quick at depleting the smartphone's battery, compared to Chrome and scored a measly 4 and half hours. Having that in mind, we chose to use Chrome when calculating the Zenfone 2's endurance rating - it's only natural that the user will opt for the more efficient solution, especially with such a great difference in longevity.

Connectivity

The Zenfone 2 ZE551ML is well stocked on connectivity options. First off, there's quad-band 2G/GPRS/EDGE on both SIM cards and that's where the second card is capped. SIM 1 also gets quad-band 3G and a multitude of LTE bands, which are region dependent.

Dual-band (2.4GHz and 5GHz) Wi-Fi 802.11 a/b/g/n/ac radios are on board as well, with Wi-Fi Direct and hotspot support.

Bluetooth is in its 4.0 version and offers A2DP support for audio streaming. We're seeing increasing adoption of the newer 4.1 iteration which fixes issues with Bluetooth/LTE interference, but not on the Zenfone 2.

A GPS receiver with A-GPS and GLONASS should provide precise tracking. NFC functionality is also present.

The microUSB port comes with USB host support for attaching your choice of peripherals and MHL support. The headphone jack is the standard 3.5mm affair, allowing you to plug in just about any set of headphones out there.

There's also a dedicated microSD card slot for storage expansion which takes cards up to 64GB.

An FM radio receiver is provided for listening to music on the go without generating data traffic. There's no IR blaster, though, so you can't control home appliances with the Zenfone 2.