I've been preparing for gnome3 for many months by running it in a virtualbox gentoo-guest machine. I missed a very important gnome3 feature by doing it that way :(
The gnome-shell desktop has a 'gestures-based' feature, which exposes the favorites menu if you move the mouse pointer *very* quickly to the left upper corner of the screen. Who knew? Well, I didn't know until yesterday because virtualbox allows the mouse pointer to slide right off of the guest window onto my real desktop without notifying the guest machine, apparently. Anyway, the active-left-upper-corner feature saves me one annoying extra mouse-click when launching the apps I use all day long. That one extra mouse-click was a major gnome3 "bug" for me, but now it's just a virtual bug :) For us old gnome2 farts who don't know where to begin with gnome3, I'd suggest installing two gnome-shell extensions that may save you many hours of bewilderment: First, the "settings center" extension, which exposes several important sub-menus that are otherwise nearly impossible to find. Second, the "system-monitor" extension, which replaces the multiload gnome-panel applet that I can't live without. The gnome extension website offers several 'system-monitor' applets, but the one I'm now using is the one written by 'darkxst'. So happy :) I strongly suggest emerging the 'alacarte' and 'gnome-tweak-tool' packages from gnome-extra. They are not installed by default when emerging 'gnome', but I couldn't use gnome without them. Happy to answer any gnome3 questions if I can.
