I was quite happy with Gnome 2. I wasn't following Gnome development, so I was somehow caught by surprise by Gnome 3. Well, gave it a try.
Gnome Shell didn't work in first place, due to the video driver or something. After seeing what's like in descriptions all over the web, I'm glad it didn't work.
Gnome Fallback was kinda useable, but many things got broken (even sacred shortcuts as Ctrl-Alt-Del or Ctrl-Alt-Backspace!), and what was left working got way harder to do, demanding many more mouse clicks or some guessing. Besides that, my desktop settings were just ignored!
I then heard about Cinnamon. Well, AFAIK, it is a workable version of Gnome Shell, which I don't like, so I didn't even try.
Then I installed Mate. My desktop was back, useability was back, my settings were back, my applets were back and my wife's satisfatcion with the computer was back. Enough, I'm keeping it.
I didn't try the other DEs. KDE is described as too much for my old Pentium IVs, and to suffer from the same ill path as Gnome, so I'll skip it. Someday I'll try the others, who knows?