I bet every real estate agent in the world would like one of these hooked up to a database of houses for sale, so they could instantly scan all the relevant information.
Is a smartphone with GPS not able to do any of this? How would Google Glass be anymore accurate than a GPS to be able to overlay the information properly as opposed to an "AR" app on a phone?
Maybe it could be useful for some things, especially games, but even in that situation, not having a HUD or anything distracting on the screen is seen as a benefit, so why would you want it IRL? Maybe it could be arranged into something more useful to you personally such as widgets on a desktop, but I can whip out my phone and check a few quick things already.
I just don't know if I want to always be seeing data. So it'd be easier and cheaper to whip out a smartphone instead of taking out my smartglasses and putting them on.
Adding features does not necessarily increase functionality -- it just makes the manuals thicker.