Why you can trust TechRadar
We only gave the Sony Xperia Z3+ three stars out of five, and one of the key reasons for that was the awful processor problems the phone had. It would heat up to levels where you couldn't even hold it, as well as crashing apps.
The slightest tasks could cause this issue, and the Qualcomm Snapdragon 810 chipset inside the phone has been named as the culprit. That meant it came as quite a surprise when Sony announced the Xperia Z5 would once again host the same chipset.
It's identical: a quad-core Cortex-A53 clocked at 1.5GHz and another quad-core Cortex A57 clocked at 2GHz, as well as an Adreno 430 GPU. That's backed up by 3GB of RAM as well and nothing has changed on the new phone.
Sony claims to have sorted the issues ready for this phone. The truth is less resounding: after some intensive testing we can assure you the issues have been improved upon, but not solved.
I installed Real Racing 3 on the phone – a very graphically intensive game – crashed my car into a wall and left the game playing for an hour straight. It came out the other side quite hot but hadn't stopped the app like it would on the Xperia Z3+.
The Xperia Z5 definitely gets hotter than other popular phones on the market – it could really do with cooling down if you want to be holding onto it to play these games, but it's not unbearable like on the Xperia Z3+.
Bearable isn't really good enough here though. You should be able to play your favourite game for a few hours, stick it on charge and keep playing without having to worry about your fingerprints melting off.
Although this has improved quite a bit on last time, if you're thinking of using the phone for intensive activities you should be warned it's bound to warm up. Video also heated up the phone a little but no more than you'd expect it on other phones.
As for general performance, the Xperia Z5 is particularly slick at manoeuvring around all my apps. Multitasking has improved on previous Xperia Z phones, and sliding in and out of apps is satisfyingly quick.
Having said that, it's noticeably worse than many of its rivals. In a techradar smartphone speed test video it had to boot up and cycle through ten apps twice, while being timed against the Samsung Galaxy S7, LG G5, iPhone 6S, HTC 10 and Huawei P9. You can see how it did in the video below.
Now, its Android rivals are all newer and packing more recent chipsets, so it's not that surprising that the Sony Xperia Z5 lost, but with a time that's almost a minute longer than the iPhone 6S it was well and truly trounced. That said, if you take the boot up time of the phone out of the equation it actually topped the HTC 10, which came as a surprise.
I ran the GeekBench 3 software on the phone a few times and it came out with an average single core score of 1,312 and a multi-core score of 4,015. Once again, when you compare it to the Xperia Z3 (which came out with a multi-core score of 2,737) it sounds fantastic.
But then compare that to Samsung's Galaxy S6 Edge, which scored 4,774 in the same test, and it makes the Xperia Z5 sound weak. It's not the best on the market, especially now newer phones like the Samsung Galaxy S7 have arrived, but that said, unless you're a really intensive user, it will provide exactly what you need.
Every time I review an Xperia product I feel like I'm moaning about the same thing, and it's the overlay that forces that anger. Sony is proud of it and how well it does for the company in Japan, but I've yet to see one Western tech critic say they enjoy the look on the brand's phones.
As more and more manufacturers drop elements of their UI to look more like stock – even Samsung has done it – it makes Sony look really outdated.
It made sense for Sony to have its own UI when stock looked rubbish, but now Google has improved the look quite a bit it's overtaken the look of the Xperia UI. Sony has taken on board some of the design changes such as the Settings bar coming down from the top – a lovely touch I wish was applied to the rest of the phone.
My main issue is with the individual app icons themselves. Once you jump into the apps, everything is looking good again with a Material Design influenced look. Just above you can see the phone app that looks clean and fresh.
I'm not a fan of the Sony keyboard either. I find the comma button is in the wrong place, so I always start adding in emoji at the wrong point, and a lot of the keys themselves are too close together. That's not really a major issue in this day and age when we have easy access to apps like Swype and SwiftKey that perform a lot better than standard options.
There's quite a bit of bloatware here once again as well with Sony bundling in generally useless apps such as News from Sociallife, TrackID and the Xperia Lounge.
It's not just stuff from Sony this time either – there's apps from Amazon, Dropbox and Kobo waiting for you. I personally don't like it being filled up with these apps when it's easy enough to download them when you need them.
There's an excellent interface setting up the fingerprint sensor, and it's a shame Sony doesn't mimic that across the board. It did feel a little patronizing with its "great, keep going" messages, but overall it was simple to set up.
The camera interface on the Xperia Z5 is nice as well. After using a Motorola phone for the past few weeks, I appreciated the camera app. On the Moto X Play you just tap the screen to take an image and I find it much better to have a clear button so you can use the tap function to focus the camera.
All the camera apps are easy to grab from the yellow button in the right hand corner, you can access your previous snaps in the top right and there's a record button just below the camera icon.
You have Android 5.1.1 Lollipop running here but Android 6.0 Marshmallow will be coming soon. Sony isn't exactly well known for its quick updates to its phones but it has confirmed it'll get the software at some stage.
Current page: Performance and interfacePrev Page Display and key features Next Page Battery
James is Managing Editor for Android Police. Previously, he was Senior Phones Editor for TechRadar, and he has covered smartphones and the mobile space for the best part of a decade bringing you news on all the big announcements from top manufacturers making mobile phones and other portable gadgets. James is often testing out and reviewing the latest and greatest mobile phones, smartwatches, tablets, virtual reality headsets, fitness trackers and more. He once fell over.