I recently became a proud user of the XGL server with the Beryl manager. In the past, a rather jerky desktop was something you were used to on Linux. Since Compiz/Beryl, it has become possible to use your graphics card's 3D capabilities as well.
Anyone who has not used Beryl yet will think: "I don't need that kind of gimmick." But anyone who has enjoyed its look and feel will think differently.
Displaying the current windows as thumbnails can be very useful while working (just press "Pause"). Then you simply select the window you want. This makes the taskbar practically redundant.
The only real problems were with my ATI graphics card. Its driver had to be recompiled.
But there were several tutorials online for that.