What people dislike about Ubuntu
Click me. The Unity desktop seems to be the biggest gripe (no surprise there). For me it's lack of action on bug fixes. I used to run the servers for an e-tailer, which ran Ubuntu. I discovered a couple of bugs which I reported to Canonical and there was a distinct lack action.
Sort of related is Linus Torvalds dubs GNOME 3 'unholy mess'. I can't comment on Gnome, but KDE4 is a similar dogs breakfast. I'll stick to IceWm for now, although I might give Xfce a run at some point. I run LXDE on one of my machines, and so far the experience has been pretty good.