Be assured, 720P video shot on any real camera (from Panasonic Lumix G series to Canon 5D Mk II/III) will blow away the 1080P and 4K from this Sony and most other phone cameras. (Cannot comment on the Nokia with the 41MP sensor as I have not seen it's 1080P video yet.)
I wish Sony would be more honest. From what I understand, the images from the Xperia Z are not even that good. Am convinced they are doing this on purpose to make people buy their real cameras or the forthcoming QX series smart phone lenses.
4k recording.. hmm.. I really don't think the quality of 4k will be good.. sounds more like a spec thing to me.. something to boast about rather than actually use... who has a 4k display anyway..
4k...to see where? on my refrigerator? and why? to fill my memory after 20 minutes? useless
OMG, my dual core laptop will grind to a halt trying to play a 4K video (even with it's dedicated 512 Nvidia card)
Phone technology is just bloody amazing the speed of its progression.
Improve your camera quality first before attempting to introduce 4k video recording. This megapixel race needs to stop.