I've been watching the videos from //Build 2015 conference, and I'm blown away by the potential I see in Hololens. I just got finished watching the case studies video, and the potential there is amazing. I though Google glass was going to be an amazing technology as well, but I don't think it went far enough. I think the device ended up too small, which severely limited it's potential application due to battery life and limiting user interaction. Hololens may be the correct form factor for this, and if it's done as well as it looks in the videos then there's a serious paradigm shift coming for user interfaces. I haven't heard any details on battery life for the device, and I think that may be a crucial piece of the puzzle. The case studies video mentioned that if you want to get a jump start on learning to develop for these devices then developing 3d apps/games for mobile is a good place to start (Unity was specifically mentioned a couple of times) for learning how to develop good UI for this type of environment. Myself, I'm going to start going through those tutorials I downloaded months ago and learning the environment, once this device hits the public there are going to be lots of opportunities for someone that already has a head start with this type of UI development. You can still never go wrong with learning the basics of good UI design, and I'll be continuing my reading and review of UI design books. Good luck and happy designing.
Here's another link I found for hololens from build: https://channel9.msdn.com/Events/Build/2015/C9-08