To all the people talking about 2 screens, it's 1 screen. They just use 2 eye pieces with mirrors to allow you to see the entire screen with both eyes (rather than half with each eye). That way there is no syncing problems and etc.
Also in the final version they plan on including multiple optic pieces so you can adjust it/customize it to your vision (so people can adjust it and not get headaches). They're looking into possibly selling optics with prescription lenses for those that normally wear glasses as well (that or they're going to try to figure out how to make it comfortable for people with glasses, don't think they've decided which yet).