Since upgrading to 12.04, I've noticed that the shortcut keys for switching applications (Super+1, Super+2...) are very difficult to use now. By that I mean that it doesn't seem to register the keypresses simultaneously, and what ends up happening is that when I press Super+1, it will type a "1" into the current application and then open the Unity launcher.
I'm quite certain that I'm hitting them in the correct order, and I noticed this behaviour immediately upon upgrading and never before that on 11.10.