I'm currently running the unity desktop shell on my development computer. I got fed up with KDE's lack of support, and the gnome-shell just annoyed me. Unity seems like a good start, but suffers from several problems. I've found workarounds for all of these, and thought I'd post them below.
One of the major changes in unity is the thin scrollbars (technically called "overlay scrollbars", I believe), which are enabled by default for all GTK applications. This is what I'm talking about (image from techgarage.com):
The problem can be avoided by turning the thin scrollbars off. How do you do that? Easy - launch the application with the "LIBOVERLAY_SCROLLBAR" environment variable set to 0, like this:
Whenever I change a setting in the compiz config settings manager (ccsm), the top panel of my unity desktop becomes corrupted. Previously the only way to fix this was to log out and log back in again (effectively restarting unity). Here's a screenshot of the problem:
When this happens you can restart unity without having to logout, or close any applications. Simply run (either by pressing Alt+F2, or in a terminal):