First, I do prefer the old interface better, but I hardly think the new one is as bad as apparently some do. In fact the new interface is more in line with Prime, Max and other service, still like old interface better.
My pet peeve is more addressed at apps that aren't updated with a proper set of features. One example:
There is a tap to zoom feature under video. Turn it on and a double tap on remote zooms AppleTv 16:9 videos to show on full screen. Netflix and Max do not support this feature - boo. Instead, I have to use vertical zoom on my TV, which does not have a per app setting, so it is a pain. But why have a 4k TV and only use a portion of it? Some apps like Max do not support the standard video positioning scroll on the bottom of the screen. I'm OK if they had something better, but their selection is terrible. it does not support Info, it does not support subtitling and audio selections, like enhanced dialog and reduce loud sounds. So worse, time to upgrade your software Max.
Finally, as a total great suggestion across all apps, how about video profiles to change color, contrast, zoom, detail, etc, like smart TVs? Same for audio profiles. Only settings currently are enhanced dialog and reduce loud sounds. How about EQ profiles including movie genre? I know people have been asking for this for awhile - it remains a good request.
Sorry folks, just trying to remain positive, it feels better when I do