I haven't tried one of these, of course, but I wonder about the trade off. It sounds like you're trading off the inconvenience of the goggles for the even greater inconvenience of staying in exactly the same location the whole time - find one of the "sweet spots", and then don't move. Maybe it's more forigiving than I'm making out, but from the description I conclude that you could only move a small fraction of the width of your head before things go screwy.
Are people truly this keen on 3D?