We've had one at our house for a few days now--even the relatively rough devkit delivers on the promise, in spades. The only thing it needs to is to be completely USB powered (probably not possible given the power envelope, or at least have a way of powering it from a battery pack for portability reasons).

People using it (we had a party recently, showed it off) do feel disorientation, mostly due to a lack of seeing where there real body is. Our hope is to integrate the point cloud from a kinect to help with that.

Oh, also, after a few drinks the impedance mismatch between what you're seeing and what you're doing is imperceptible. :)