The main reason for shooting in 4k is that you can down sample it to 1080p and it does look a bit better.
Otherwise 4k is kind of overkill, you do not need it that much, but some specific things, like shooting landscape, scenery and so on, wildlife etc. That is where 4k really shines.
But that is for personal stuff, when it comes to TV shows, movies and other things, yes then 4k is real nice, but as this is a action camera it has limitations. But sure nice with a upgrade, better or equal to gopro hero 4 black, but with a much nicer price point.
I would realy like to see a "cage" for the camera, so you could have your (future) bluetooth microphone mounted, and perhaps
extra power source and attach a gimbal. A good camera in a super small formfactor and easy to carry around everywhere
anytime, compared to a big mirrorless or dslr.
And image quality is great, as long as you do not use it during bad light or nighttime.