I really hope they get the accurate tracking and depth and getting objects to "stick" where they belong in 3d space correctly, without moving out of place or floating in a wrong way, with quick head movement. If they can do that, most of the battle is won and it will be amazing.
Edit: although, of course they'll need some intelligence on the surroundings to identify surfaces and stuff. But imagine like re-decorating your work room, adding scifi textures or something, and maybe pipes or whatever ;p
But they showed footage "through the eyes of the wearer" and they let press have a hands on demonstration, so it's not like they can really fake anything.
I did see a tiny bit of judder in the footage that was supposed to be exactly what the person wearing the glasses would see, but it was hard to tell.
In case any reader here weren't aware how Kinect works, it sends to the developer a 2D image of the depth. Of course as walod says, there's work to do to identify surfaces (as you can see on the image below, background elements are excluded).
Edit: although, of course they'll need some intelligence on the surroundings to identify surfaces and stuff. But imagine like re-decorating your work room, adding scifi textures or something, and maybe pipes or whatever ;p