4K, or Ultra HD, is definitely the 'in-thing' right now. If you're buying a new TV then there's a high chance it'll have a 4K display and even computer monitors with UHD panels have started to become more affordable. Then there's the fact that every high-end Android smartphone in recent times can boast "4K video recording" as a feature.
But do we really need 4K displays on smartphones just yet? Sony thinks so, even if the execution in the Xperia Z5 Premium is seriously limited. We've got a couple of arguments in the for and against column.
For - All things VR
While not necessarily something Sony has got too involved with yet outside of its PlayStation VR project, products like Google Cardboard and Gear VR would very much benefit from having more pixels to play with. When the phone is what's doing the legwork and it's mounted just a few inches from your eyeballs every pixel counts. It stands to reason then that a 4K display would be better here.
Sometimes, more is just better. Regardless of what anyone says.
For - Media consumption
Gradually more 4K content is becoming available, though it's questionable whether or not the phone in your pocket is the best device to watch that on. But if the content is available then why wouldn't you want to get at it on any of your devices?
Coupled with smartphones seemingly being on an unstoppable increase in size and we're fast arriving at the point where watching an Ultra HD movie on your phone would actually be a good experience, particularly for folks on the move. Perhaps not a mass market adoption, but if it's there, why wouldn't you want to use it?
Against - Can you really see the difference?
Part of the issue is that on a 4K TV you can totally tell the difference when stepping up from 1080p. On smartphones we've had 2K, or 1440p, for about 18months now and some would say it's tough to tell the difference on that scale. Bump up to 4K on similar sized displays and can you really, honestly, tell the difference between 2K and 4K? Aside from knowing it can play 4K content at native resolution, how much benefit will you gain in regular, every day use of your phone?
And it then ties in to the next couple of points.
Against - It'll probably drain the battery a lot quicker
Battery technology will continue to advance, as will software tricks to help you get the most from it. Doze, in Marshmallow, is one such advancement, but sometimes you have to get down to brass tax. A large, 4K display will suck more life from your battery than an equivalent sized 720p, 1080p or even 2K display. It's one of those things we can't escape from and as phone makers all seem involved in a race to the thinnest, something somewhere will have to give.
Or you'll forever need to keep a battery pack handy.
Against - Price
This will eventually become less of an issue but right now the Xperia Z5 Premium is a fine example. It's very expensive. In the UK it costs around £600 for a phone that's 90% the same as the smaller Xperia Z5. Regardless of Sony's execution, that's a lot of money. Sure, Apple can command that price and people flock to pay it. But can we honestly say the same of anyone not involved in the Cult of Apple?
Right now especially, is there any feasible reason to pay a large extra premium?
That's just a few of ours, but what do you think? Be sure to drop us your own opinions in the comments below!