It was fun for about 5min, until I realised that I didn't actually NEED any of the functionality it offers. The speech recognition was very good for me, but completely refused to understand my girlfriend. I'm left with a slight headache and I can definitely feel my right eye has been strained :-/
The units all become VERY hot in use and are actually quite heavy. The contact speaker simply refused to transmit audio effectively to my skull.
Overall the device is quite intrusive despite sitting just above my field of view (an intentional position by Google).
The one application that was really good, was the augmented reality star finder... But again, a novelty not a function :-/
A nice experiment, but it's not a product.