Biggest gripes:
1) touch screen nav on a user profile is nearly impossible to scroll vertically, as any left/right movements will cause you to jump sections (videos→playlists, etc)
2) Windowed mini-viewer (is a total PITA)
3) The "full screen" mode never seems to lign up where I'm either cropping part of the picture out or I have some stupid white slider-looking thing in one corner of my screen.