Yes I also think that screen flickering is cause because of compiz. Everything is fine until some part of the application which is on workspaces 1, is also on the workspace 2. If that happen (often) and whenever I press super+w I got some crazy effects. The solution is to press super+w 2 times. It's not such big problem but it's annoying. However Gnome shell doesn't have this problem that's why I think Gnome shell is better.
@jbicha I will definitely test alpha of gnome shell as it will be released.
Keep up the good work.