Whilst I don't deny the tech demo looked good, at the end of the day that's all it was. A tech demo. Microsoft showing off what they can do, not the product you will receive. I've followed the HoloLens since they announced it, and there's been many hands on reviews to date. Unfortunately the biggest issue is that it's not as immersive as they'd have you believe in the demonstrations. The best example I've head is that it's like looking at a mobile screen at arms length. Sure the virtual world surrounds you, but you must look around left and right, up and down, just to see a reasonably sized object. Nevertheless, the technology they have is very impressive! I just wouldn't hold your breath for anything like you've seen until aleast 2020. :P
Sadly, after my initial excitement and post-demo research. It seems like this may not be as amazing as I'd hoped. Granted, I think it will still be very cool. It seems the field of view is much narrower than I'd expected.