I didn't touch Ubuntu until I have to upgrade about 2 major versions. Actually I was forced to upgrade because the old one wasn't supported any more. I kept updating by default until it was 10.04, and no more. I was happy that nothing broke. There was but you can fix it somehow or leave it alone.
Now when I was totally enjoying it, especially the gnome applets, I saw the new 11.04. I tried to upgrade and find out that I have to upgrade to 10.1x first. You have to push a button instead of by default.
After two major upgrades and fixed some broken stuff, only to find out that gnome applets are history. So what worked on my last goodies post won't work at all, or looks differently.
I like the new Unity 3D GUI. It's space saving. In MS Windows terms, the whole status bar integrates with the quick launch area, and it's auto hide. Also title bar of applications integrate with the menu bar. So it's back to Windows, you have only one bar normally visible. Also the scroll bar becomes hair lines when you are not using it.
There are themes and 3D effects but I'm not up there yet.
I switched back to the Ubuntu Classic GUI. You can do it when you login.