I think GNOME3 is breaking *nix philosophy: do one thing and do it well; to be highly configurable. You have freedom to use compiz in GNOME2, but not in 3. There are a lot of good GTK2 themes but gitg and d-feet have hard-coded styles so only default GNOME3 theme will look sane. Super+p is somewhat hard-coded and you cannot customize it ... and there are more annoying issues. I am happy that mate-desktop is still alive.