Sony made smartphone history at IFA 2015 this week by launching the world's first 4K-resolution smartphone, the Xperia Z5 Premium. With an Ultra HD screen. Understandably, it's one of the big devices of the show, and we've since had some extra hands-on time (following on from our first impressions).

In short, Sony's brought its familiar design language and software experience to a phone with a ridiculous 806ppi display and insanely shiny mirrored back. At 5.5 inches, the Premium feels noticeably bigger than the regular Z5, but not unmanageable.

As for performance, the phone seems to cope admirably with the 4K display resolution, and we noticed no lag during our time with a demo unit in Berlin. We'll have to wait and see how the phone performs when release day rolls around, but at first glance Sony appears to have managed to pack a Snapdragon 810 and a 4K display into the same device without any ill effects.

MORE: Xperia Z5 Premium: Up-close and personal with the world's first 4K phone