And to be at all comfortable with it I'm using about 15 extensions.
So now I see Gnome Shell as basically the core of a framework to develop your own desktop system. Not ideal, but I like it more than xfce (and cinnamon, last time I tried it).
Currently GS on Gnome 3.6 as provided by the Gnome Ubuntu Remix 12.10 has my attention, seems a good fit to my end user like use cases. The only plug-in at present is the one to put the hibernate command back on the power/system settings menu.
I find GS gives me the illusion of being more responsive (perhaps because when invoking the search screen there is no dynamic search going on) and is somehow 'quieter' in operation.