Sony Xperia Z5 Premium review: A 4K let-down with massive battery drain

Back in September 2015, Sony was the first manufacturer to release a 4K smartphone to the market. One would have thought that Samsung, LG or Motorola would have released it before the Japanese company. Instead, it was Sony that made the leap to 4K with the Xperia Z5 Premium.

Despite its name, the Z5 Premium has more in common with the ill-fated Xperia Z3+ than the rest of the Z5 range. This is partly down to its design, where the company decided to ditch that frosted glass design for a glass, mirror-like finish. The effect is more subtle on the other colour choices, but it makes little difference when none are as easy to grip as the standard Z5. This also attracts a lot of fingerprints, which distracts you from its ‘premium’ status.

It should be noted that Katharine’s review (below) review was conducted when the phone was priced at £600, but it can now be found for around £400. At the time of the original review, its 4K resolution wasn’t fully supported across Android apps, but since, this has been fixed – making it easier to recommend the phone for those looking to invest in 4K.

^ The Chrome version of the Z5 Premium has a full mirror finish, but the gold and black models aren’t quite so reflective

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Sony Xperia Z5 Premium review: 4K Display

Of course, the main attraction is that 3,840 x 2,160 resolution display, which across 5.5in gives the Z5 Premium an insanely high pixel density of 806 pixels-per-inch. That’s more than twice as sharp as the iPhone 6S Plus and 1.5x as sharp as the LG G4, both of which have 5.5in, but only resolutions of 1,920 x 1,080 and 2,560 x 1,440 respectively.

When I first reviewed the phone, it was incapable of rendering apps at 4K and instead used a standard 1,920 x 1,080 resolution for everything outside of Sony’s Album and Movie apps. This was due to Android 5.1.1 not fully supporting 4K.

Thankfully, Android Nougat, which is a free update for Z5 Premium users and fully supports 4K. This means your phone will now render everything in 4K – making a huge difference to the overall look of the display.

It should be noted that you can see the difference between 4K and 1080p, but you do have to hold the phone rather close to your face to appreciate it. Viewing it from a normal viewing distance, and the crisp detail becomes significantly harder to pick out. It’s hardly the most compelling reason to shell out £600, but Sony hopes it will at least provide a bit of future-proofing in the device for when app developers (and Android) eventually catch up.

Sony Xperia Z5 Premium review: Battery Life

Sony’s chief reason for rendering at 1,080p is to help preserve the phone’s battery life, as, understandably, rendering at 4K all the time would tear through the 3,430mAh battery in no time at all. It doesn’t seem to have done a particularly great job, though, as the Z5 Premium lasted a pitiful 9h 38m in our continuous video playback test. This is the worst result I’ve seen across the Z5 family, with the Z5 lasting 11h 29m and the Z5 Compact managing an even more impressive 13h 21m. It’s also pretty poor compared to other phablets, as other handsets with batteries of this size have all lasted well into double figures.

Sony Xperia Z5 Premium review: Display

Display quality doesn’t quite measure up to the normal Z5 either. While its 97.6% coverage of the sRGB colour gamut means it still has one of the best IPS displays around, its accuracy levels are just a fraction below the Z5’s. When I compared them side-by-side for example, the Z5 Premium had a noticeably cooler overall colour temperature compared to the Z5, which meant that warmer colours didn’t look quite as rich or punchy.

The Z5 Premium’s screen also isn’t as bright as the Z5’s, as I only measured a peak brightness level of 455.25cd/m2 compared to the Z5’s massive 684.25cd/m2. As a result, whites also weren’t nearly as clean and pure on the Z5 Premium as they were on its little brother, which also had a knock-on effect on its overall colour vibrancy. It’s not all bad news, though, as the Z5 Premium’s contrast ratio of 1,255:1 and black level of 0.36cd/m2 beats both of its smaller siblings, leading to deeper blacks and more detailed images.