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.

Sony Xperia Z5 Premium review: Performance

Aside from the display, there’s very little else to distinguish the Z5 Premium from Sony’s other two flagships, as they all use the same octa-core, 2.0GHz Qualcomm Snapdragon 810 chip and the same 23-megapixel camera. Admittedly, the Z5 Premium proved a little faster in our benchmark scores, with a score of 1,349 in the Geekbench 3 single core test putting it around 100 points ahead of the Xperia Z5. A multicore score of 4,667 is more than 600 points in front, making it even faster than the Galaxy S6.

In practice, though, it took the Z5 Premium just as long to loads apps as the Z5. It’s still pretty quick, but does little to help justify the Z5 Premium’s higher price. Web browsing performance was also pretty equal. With a score of 1,524 in Peacekeeper, the Z5 Premium coped beautifully with complex web pages, and didn’t even stutter when it was faced with images, embedded videos and adverts within a single article.

Likewise, graphics performance was nigh on identical; 1,565 frames in GFX Bench GL’s offscreen Manhattan test produced a highly respectable average of 25fps, the same as the Z5 Compact and just one frame behind the Z5. With this much power behind it, games such as Hearthstone proved no problem at all for the Z5 Premium, and simpler titles like Threes ran beautifully.

Sony Xperia Z5 Premium review: Camera

There was little to separate the Z5 Premium’s camera from the vanilla Z5’s. Images were well-exposed in our outdoor test shots, and colours and contrast levels were excellent, but look closer and there are almost identical levels of post-processing noise and grain. Objects in the centre of the frame were reasonably sharp, but further out it became noticeably fuzzier, with small details becoming all but lost in the haze. Switching to Manual mode and enabling HDR didn’t help matters either.

^ The camera was a little disappointing outdoors, as there was a lot of post-processing noise present at full resolution, particularly toward the edge of the frame

Thankfully, indoor performance was significantly better. Textures in our still life arrangement were still a little blurred in low light, but grain was kept to a minimum across the frame and colours looked pleasingly neutral. There was also an excellent level of contrast on show, and the flash kept images nice and clean.

^ In low light, textures were a little hazy, but overall there wasn’t as much grain as our outdoor shots

^ With our external lamp turned on, the Xperia Z5 Premium produced excellent indoor shots, showing plenty of detail and crisp, neutral colours

Sony Xperia Z5 Premium review: Verdict

At launch, the Z5 Premium didn’t do enough to justify a £600 price tag and being chosen over the original Z5. With better 4K support on Android and generally across apps, the Z5 Premium is a fast, phone that has a stunning display. Unfortunately, this does come at a cost, where its 4K display drains a lot of battery – even at 1080p. Adding to its problems, its camera is a mixed bag, with excellent indoor shots, but noisy outdoor shots. Nevertheless, the Sony Z5 Premium is a good 4K smartphone, that now has 4K support, but does still lack the edge over non-4K smartphones.

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