Sony Xperia Z3+ review: Too hot to handle - and that's not a good thing

Sony Xperia Z3+ review:

Smartphone makers' obsession with thinness has claimed its first victim. By combining a body thinner than its predecessor and a processor with known performance issues, the Sony Xperia Z3+ is a smartphone that simply does not work properly. Sure, it makes calls, sends text messages, browses the internet and plays music – but it has an overheating problem that can predictably and regularly be triggered by using the camera.

The phone is not a complete write-off, though. It looks and feels like a true premium handset, it has Android Lollipop, a good camera (which is not to blame for the overheating), is waterproof without needing covers over its ports and has expandable storage.

Let me end the introduction here and try to be balanced about this...

Sony Xperia Z3+: Look and feel

Very little has changed with Sony's flagship smartphone since the Xperia Z1 arrived nearly two years ago, in September 2013. You could optimistically call it the Porsche 911 school of thought, making small changes each generation to perfect a winning formula; but where cars are updated a couple of times each decade, Sony has been tweaking the Xperia Z line up twice every year.

Criticism aside, the Z3+ (inexplicably known as the Z4 in some countries) is a handsome handset. A metal chassis finished in glossy black is the meat in a glass sandwich protected by nylon corner caps to limit damage caused when you drop it. Or when it slides off the sofa, which it will, because that glass back acts like a freshly oiled slip-and-slide on anything but a completely flat surface.

The phone is 6.9mm thick and weighs 144g – 0.4mm thinner and 8g lighter than its predecessor, the Xperia Z3. It is slightly larger than an iPhone 6 but has a smaller screen-to-body ratio, fitting in a 5.2in panel compared to the iPhone's 4.6.

My only complaint with the Z3+'s design is how you can feel the earpiece vibrating against the rear case when the person on the other end of the line is talking, even when the volume is turned down. A side effect of making the phone so thin, I imagine.

Sony Xperia Z3+: Screen

Speaking of the screen, Sony has given the Xperia Z3+ the same Full HD 1920 x 1080 resolution as the Z3, Z2 and Z1 before it. The smartphone market is split when it comes to resolution, with Sony, Apple and HTC all sticking with Full HD (or slightly less, in Apple's case), while LG and Samsung have made the jump to 2560 x 1440, known as 2K.

To my eyes, the Z3+ would not benefit from a higher resolution. You can hold the phone right up to your face and it still is not possible to see individual pixels. It is a quality display with good contrast, accurate colour reproduction and wide viewing angles, but let down a little by a less powerful backlight compared with other flagships.

I found I needed the screen turned up to 100% most of the time, even indoors on a cloudy day –doing that with an iPhone 6 would have burned my retinas out in minutes. Using the phone outside on a sunny day can be tricky and the issue is made worse by a weird reflection from the touch panel of the display – a trait shared by the Z3 – and how the picture almost entirely disappears at some angles when viewed through polarising sunglasses.

That last point is a drawback shared by many other phone and laptop screens – including MacBook Pros – but it can be overcome, as Apple has proven with the iPhone 6, which is unaffected by this weird side effect of wearing polarising glasses.

Sony Xperia Z3+: Camera

Sony has plumped for the same 20.7-megapixel it has been using in its flagships since the Z1 arrived in 2013 for some time. It is a fairly decent camera and produced good, well-lit shots with good detail and it even has a fairly usable digital zoom. Seeing the same lens and sensor, no matter how good, for a fourth generation is disappointing though, especially when Samsung, Apple, LG and even HTC bring something new to the table every year.

Sony's Superior Auto mode does a sterling job of taking good quality photos with minimal effort, adjusting well to lighting and movement. But speed is an issue, though, as the camera takes a good second or so to focus when you press the shutter button, and a further two seconds to process and save the photo before another can be taken.

A wide suite of shooting modes let you add augmented reality objects to scenes, such as dinosaurs, and new for the Z3+ is AR Mask, which creepily pastes the face of a different person –or animal – on to your own, even moving the eyes, mouth and other facial features in time with your own. Weird, but good for sending ridiculous Snapchats.

Sony has updated the front camera from 2.2MP to 5.1MP, which will no doubt be big news for selfie fans.

Sony Xperia Z3+: Software and Performance

I don't know whether to lay the blame entirely at the door of Sony or Qualcomm, who produce the Z3+'s Snapdragon 810 processor; perhaps the blame should be spread equally across both, because this phone's performance and overheating issues are a major concern. Some reviewers have gone easier on the Z3+ than others but all who have tried the phone has reported issues with rapid overheating, particularly when using the camera.

Although the phone can take photos like any other – albeit slowly, as outlined above – shooting 4K video or using any of the AR features causes the handset to overheat in just a couple of minutes, forcing the camera app to close.

The same happens when opening the camera after playing a graphically intense game such as Real Racing 3. The same happens (only more quickly) when you use the camera on a hot, sunny day.

Recording HD video causes problems too, with footage becoming very jerky after just a couple of minutes, making recordings largely unwatchable. Even simple tasks like scrolling through Twitter causes a small area on the rear of the phone to get incredibly hot in just a few minutes. Launching the camera app immediately opens a warning that the phone's temperature is rising, followed by a notice to say the app will now close.

Naturally, battery life takes a tumble when the Z3+ is running hot, and while it can just about survive two full days of very little use, open a game or use the camera several times and you will be down to 20% before the first day is over.

Sony says it is aware of the problem but describes the phone overheating and camera app closing as "normal operation of the device and no cause for concern," adding that to "further increase comfort" a software update is planned "during the summer period to limit additional heat generation under normal use". At the time of publication this update had not arrived.

As for software, the Z3+ runs Android 5 Lollipop with Sony's usual range of user interface tweaks and extra applications. It is an attractive set up but still annoys me with duplicated applications. Would you like to open a video you shot in Photos (Google's app) or Video (Sony's app)? You get asked the same with photos and it is just plain confusing, especially when videos plays as previews without opening either.

Sony Xperia Z3+: Verdict

In its current state, I cannot recommend the Xperia Z3+ to anyone. If the camera app did not have any fancy AR features or 4K video, and only overheated when worked incredibly hard on a very hot day, then fair enough – it would be an 8/10 phone that lost a couple of points for being a very small upgrade on its predecessor.

But it does have these features and Sony has always said how good the cameras are on its phones. For its camera to fail so often and so easily is embarrassing and unacceptable from any smartphone, let alone one that costs over £500. An estimate, because Sony could not get a European or UK retail price to me at the time of publication.

What was in the first place a mediocre update – from a company that does not appear interested in the smartphone market anymore – has arrived in desperate need of a fix from day one. This review will be updated when/if the software update arrives.