Long video but worth watching for those curious about the Rift. It starts to shed some light on the practical difficulties of combining head tracking with mouse input. Valve put some work into trying to solve it. It's nice that they gave the player these different modes to try, but none of them seemed like a real good solution. It was interesting to see that guy's reaction to the last mode which effectively disabled head tracking. Completely intolerable. As I suspected, once you've tasted the head tracking it could be difficult to go without it.
I need to try this thing myself. But at the moment, I still think it's going to be fantastic for vehicle sims and only so-so at best for FPS games.