I don't want to start a flame war, but I've been unable to adjust to Unity. So I've been using Xubuntu for some months now. I just installed the Xubuntu packages over my Ubuntu 11.10 from the instructions here: http://www.psychocats.net/ubuntu/xfce.
After installing Xubuntu, some things still seemed to be weird. Much of it I could imagine might have to do with the fact that I had a lot of perhaps unnecessary Ubuntu stuff hanging around my system. So yesterday I finally followed the excellent instructions at: http://www.psychocats.net/ubuntu/purexfceoneiric to get rid of the unnecessary stuff.
I had to reinstall LibreOffice and a few other packages after following the instructions. It's worthwhile to capture the output of the command given by the link above, so you can see what's been removed.
I had one obscure problem that gave me many hours of angst. When I restarted my computer, it wouldn't boot. By booting to a live CD and checking /var/log/syslog, and Googling, I discovered that /etc/lightdm/lightdm.conf was sending me to the unity-greeter. I had to change /etc/lightdm/lightdm.conf to look like this, and then I could happily boot again:
I knew that after switching to Xubuntu but before following the above instructions, my startup was still going to the Ubuntu login screen, rather than the Xubuntu login screen. Part of the reason I was trying to go to "pure" Xubuntu was to get rid of the Ubuntu login and get to a pure Xubuntu experience.
I can't say enough good things about pyschocats. She has done an excellent job of documenting a number of tricky topics.