My XFCE4 session still works fine in Ubuntu 12.04 - a bit better since the dragging multiple items bug is fixed.
The Mint Gnome Extensions repo was disabled, I haven't gotten around to reenabling that and retesting it since I mostly use XFCE4 anyway, but I did log into Gnome Shell and it still works fine too.
Ditto "Gnome Classic (no effects)" although obviously it isn't Gnome Classic - fare warning for anyone still on Gnome 2 who expects to be able to do simple things like arrange applets on your panel, move the clock somewhere less crowded, and, oh, have applets.
Oh. On my SO's system, the event calendar seems to work better in Unity than in Gnome Shell - in Unity the events area expands nicely. In Gnome Shell it is a crumpled up little unscrollable thing.
Minor annoying thing for me. Iagno now locks up every other game and is very sluggish. Only tested in Unity 2D on SO's machine.