I tried them out and found the same thing as the author. The fact that someone dared to take a different approach gathered them a large amount of attention at CES but the 2min demo had me a bit dizzy for a good 10 minutes.

You inevitably have to look up to see the display and it's also a constant struggle to aim as best as you can to be able to see what's on the display effectively.

It's important that people in the industry try and test different approaches though!