There no built-in storage variants with the Xperia Z5 Premium – it comes with 32GB as standard, with microSD support for up to 200GB. This gives you up to 232GB of space, and the basic software starts eating into that fairly quickly.
When you first boot up the phone, Android takes up some 10GB, leaving you with around 20GB to play with before you'll need a microSD card.
I found myself filling that up quite quickly with music and apps, so I'd certainly recommend getting a card – the Sony Xperia Z5 Premium can accommodate the biggest cards available, so lack of space isn't going to be an issue.
The Sony Xperia Z5 Premium comes with Sony's own Music app preinstalled, so any music you load onto the phone will play through this. The app has sections for podcasts, genres, albums and songs, and it's easy to scroll through your tracks.
You can't easily access Sony's PlayStation Music service through the app any more – it's just listed as a service at the bottom of the app screen, and boots up a separate app when you select it.
It's the same for Spotify, or any other streaming service you're signed up to.
The Xperia Z5 Premium also comes with Google Play Music, enabling you to download a wide variety of albums and songs.
The front-facing speakers on the Xperia Z5 Premium aren't the best money can buy. They get the job done, but they don't impress as much as HTC's BoomSound speakers, for example.
There's a separate Video app on the Xperia Z5 Premium, which comes with Sony's branding all over it and a few video clips to get your started.
Some 4K videos are included, so you can show off that 4K screen straight out of the box, without having to shoot your own footage or download videos.
Which brings us to another issue with the Sony Xperia Z5 Premium: even though you have a gorgeous 4K screen, it's hard to get hold of content to watch on it.
You can head to Netflix for 4K content, but this is restricted to a number of the service's own shows, such as House of Cards or Daredevil.
There's no specific 4K streaming service, and it would have been nice for Sony to offer a few ultra-high-definition movies on its own video service.
PlayStation Video is fine, but without that standout high-resolution content you're not going to lure people away from streaming services, or from buying content through Google Play – and Google's service only goes up to Full HD right now.
With a strong processor setup and 3GB of RAM, the Xperia Z5 Premium is great for gaming.
Playing through Real Racing 3 and Hearthstone were both a breeze, with none of the stuttering you can experience on many phones.
As mentioned, there's also the option of hooking up PS4 Remote Play, which means you can enjoy your PlayStation 4 games on the phone – and performance will depend on your internet connection, obviously.
PS4 Remote Play is a great selling point for Sony's devices, and it's only going to get better as Sony expands the service, eventually enabling you to play games without your phone having to use the same internet connection as the console.