I wonder whether it would be disorienting and disconcerting, especially in the less visually astounding games. Imagine playing a Mario game in this, for example. Being in a cartoon world would freak me out. But for something like Skyrim or Mass Effect? Yeah, I can see this being a great addition to the gaming experience.
The other thing I'm not sure about is using this in conjunction with traditional controllers. Now that you're basically inhabiting this virtual world, interacting with it through something like an Xbox controller seems ... wrong. A controller's going to take you out of the experience, don't you think? I'd want special gloves or something instead of a controller. (Dear spaghetti, imagine how ridiculous-looking such a get-up would be.)
Why haven't we discussed this thing yet? Thoughts away!
Edit: oh, right, I forgot. The Oculus is not coming out with Doom BFG because the game couldn't be ready in time. Oh well.