I regard Unity and Gnome shell as still being experimental, and not delivering a very comprehensive or polished experience. If you want to get serious work done then stick with Gnome 2.x (for example Mint 11).
Like it or not (and I'm ambivalent), what Ubuntu ships is, almost by definition, not experimental. They are desktop Linux in the minds of most.
And, to be honest, GNOME 2 is still pretty lacking. I know a lot of GNOME team members past and present, and I like and respect most of them for a lot of work put in on a pretty thankless project, but the results aren't there compared to Windows or OS X.
