I have Gnome Classic installed from my 11.10 install. Whenever I try to boot into it on 12.04 beta, it gives me a black screen and does not load. Is there a way to see what is going on that it doesn't want to load? I really want to give classic a try.
Compiz with gnome classic on 12.04 is extremely buggy. For starters it takes a very long time to load (it shows a black screen for nearly a minute.) Perhaps you just needed to wait a bit longer?
In any case, once it does load there are lots more bugs, graphical and otherwise. All of these bugs are caused by compiz 0.9.x. The only sensible way to use gnome-panel with compiz is to downgrade compiz to 0.8.x, though this will mean you cannot use Unity on the same machine.
It's also possible to enable metacity compositing in Gnome Classic (no effects) by using gconf-editor to set "/apps/metacity/general/compositing_manager" and "/apps/metacity/general/compositor_effects" to True. However, this does not give you everything that you get from compiz.