I have really enjoyed Unity. I think there are a lot of very good UI choices that are better to the normal gnome desktop. I am bummed to hear that alt-tab affects all workspaces. That is one of the things that drove me crazy on OS X.
I just installed compizconfig-settings-manager, and in the Unity plugin, there is a setting where you can tell Compiz to prefer applications in your current viewport. I am no longer as concerned about the alt-tab change now.
