The Sony Xperia Z2 is an Android phone, but, as yet, hasn't been upgraded to the very latest version of the OS.

Sony Xperia Z2 review

That translates to Android 4.4.2 KitKat, rather than Android 5.0 Lollipop. What's more, it's not the stock version you'll find on the Nexus 5.

Sony has stuck its own user interface over the top, but it doesn't have a catchy name like Samsung's TouchWiz or HTC's Sense.

Sony's overlay is no where near as dominating as Sense, offering up a lighter skin which adds a few additional touches here and there to an already solid Android platform.

With a powerful 2.3GHz quad-core Snapdragon 801 processor and 3GB of RAM running the show behind the scenes you'll find general navigation around the Xperia Z2 fluid and lag free.

I was able to skip between homescreens, launch an app laden multi-tasking menu and fire up the camera app from the lockscreen using the physical key on the side, without any hint of slow down.

Head into the app tray, slide from left to right and a sidebar menu appears with a variety of ways to order your applications, from alphabetical or most used to installed or your own order.

There is, sadly, no way to hide any unwanted pre-installed applications which Sony has blocked from being deleted on the Xperia Z2.

Sony Xperia Z2 review

That's a bit frustrating as the Xperia Z2 does have a number of pre-installed applications and I found that the majority were regularly overlooked in my day to day usage.

Dive into the display settings and you'll find the increasingly familiar "tap to wake" feature. Enable it and you'll be able to wake the screen of the Xperia Z2 with a simple double tap of your finger on it.

It only works to turn the screen on, double tap again and it won't switch your Xperia Z2 back to standby. Overall then the feature is a little half baked, failing to make the same impression as the LG G2 did with KnockOn.

That said, it's still a handy little feature as it makes it easy to check if you have any notifications, or just to see the time and date.

Drag down the notifications bar and you'll find a very uncluttered offering, with just the date and time above any notifications you may have. It's a lot cleaner than LG's and Samsung's implementation which shove a load of setting options at the top.

This is being updated again to make the Z2 match the Xperia Z3 in terms of a more refined interface, plus Android Lollipop will be dropping in the new year.

I prefer Sony's minimalist implementation as it meant I could see my notifications more easily, while quick settings were easily accessible in a second tab.

Sony Xperia Z2 review

By sliding two fingers down from the notification bar you'll be thrown straight into the quick settings tab, while the single finger slide will take you to the more traditional notification view.

Sony is also keen of automating a lot of your everyday processes. Plug in a set of headphones or the USB charger and a pop up will appear on screen prompting you to take action.

In the case of detecting headphones, you can set the Xperia Z2 to automatically start playing music as soon as you stick them into the handset.

The music doesn't have to come from the dedicated Walkman app either, with the Z2 allowing you to select whatever app you want - Spotify in my case. You can also have the Xperia Z2 pause your music when you remove the headphones.

Once you've set this up you won't see the pop up again, or if you don't want to bother you can check the "don't show me this again" box so you're not constantly bombarded.

Turn Wi-Fi on and you'll spy another message, this time the Xperia Z2 wants to help you optimise battery performance.

Sony Xperia Z2 review

It's asking you to activate location-base Wi-Fi, where the Xperia Z2 will automatically turn Wi-Fi on when you're near a saved network.

Leave home, for example, and the Xperia Z2 will detect you've left the reaches of your router and switch Wi-Fi off until you get to the office, where it'll come back on (if you've saved your work's network).

It's not clear how much power this saves, but every little helps - although in general the Sony Xperia Z2 is pretty efficient. More on that in the battery section of this review.

While I found general performance to be on par with the other top mobiles on the market, there were times where the Xperia Z2 appeared to lack the zip of its rivals.

I've already raised the speed issues surrounding the Background Defocus effect in the camera app, and other features in here can also be a little tardy.

I ran the Geekbench 3 benchmark test on the Sony Xperia Z2 and it averaged 2765. That's a decent score, but it was bettered by both the Samsung Galaxy S5 (2905) and HTC One M8 (2857) in their TechRadar reviews.

Interestingly, the Sony Xperia Z3 scored a lower Geekbench 3 score (2737) than the Z2 despite having a slightly higher clockspeed. This means that on paper, there's very little difference in raw performance between the two.

However, as I've already said, the Xperia Z2 is certainly no slouch, and so if you're upgrading from the Xperia Z you'll see a big difference in performance.