Now that compiz works with AIGLX, I have switched back to compiz from beryl. Beryl has been working well… but is a but buggy and has an aweful configuration tool. Compiz is amazingly stable and gnome-compiz-manager is a pretty simple configuration tool. It doesn’t give you an interface to configure a million and one effects like beryl-settings does. But it gives you what most people care about.
We will continue to maintain both in the foresight repository, compiz as stable and continuous bleeding versions of beryl from svn. So you can choose 🙂
Personally, I think I will stick with compiz. It is nice, and doesn’t get in the way.