Once you start mousing into the "hot corner" in Xfce, GNOME Classic, or plain old GNOME 2 -- all systems where there is no "hot corner," you pretty much know you've committed to GNOME 3 and GNOME Shell.
I'm not trying to be a GNOME Shell fanboy. It doesn't gain me any credibility not to hate on GNOME 3.
But I gave GNOME Shell a try (GNOME 3.4.2 in Debian Wheezy, to be exact), and despite having GNOME Classic, Xfce 4.8, even Fvwm and Fluxbox, on this machine, I'm using the Shell 98 percent of the time.
Once my muscle memory drags me over to the hot corner, it's nice for it to actually be there.