I'm kinda baffled by all the people in these threads talking about platformers or fighting games. That's completely missing the point, which is very obviously not to replace traditional gamepads, but to complement them.

Even talking about competitive FPSes or DOTA sort of gets it wrong. Among the few games Valve prominently displayed in their announcement were Europa Universalis and Football Manager, turn-based mouse-driven games. That is where this controller should shine. It allows you to sit back and relax while playing thoughtful games that would be impossible with the typical gamepad.