Although the Android TV OS runs more quickly and stably on the 55PUT6400 than it does on Sony's current Android TVs, it still doesn't feel to me like a very helpful interface overall.
Its recommendation system doesn't seem very effective, its layout seems rather random and inefficient, it doesn't seem specially well tuned to helping you find your favourite types of content, and worst of all it's hardly customisable at all.
The 55PUT6400's settings menus, meanwhile, do a solid job of trying to organise the huge amount of features they're tasked with carrying. But the fact that you have to spend such a long time in these menus trying to optimise the look of the TV's picture for different types of content doesn't do the set any favours where ease of use is concerned.
Philips is one of the best brands around for managing to get good amounts of audio power out of very slim TV frames, and this talent holds good for the 55PUT6400 too.
There's enough power, for instance, to ensure that the soundstage sounds large and involving without losing cohesion in its journey beyond the confines of the TV's bodywork. Voices sound credible and nicely rounded too, and the mid-range has enough space in it to move through a gear or two when requested by an action scene.
There's lots of detail to be heard too - though sometimes a relative lack of bass can leave this detailed exposed to the point where it starts to sound a touch harsh.
This is, of course, one of the 55PUT6400's strongest suits.
There really isn't any 55-inch 4K UHD competition around at the £749 price level, so if that's your budget and you want to get the biggest 4K TV you can, then the 55PUT6400 is almost by default your only place to turn.
I would point out, though, that if you're willing to sacrifice five inches of screen size the stronger-performing Panasonic 50CX700 is now available for a little bit extra cash.