I think the use case is brilliant, if albeit niche. I would never wear them in everyday life but when travelling I found myself wanting something like this to capture memories, moments or just "atmosphere". A mobile camera doesn't quite cut it because it's hard to get an authentic angle, especially if you're moving. I'd rather not wear glasses when i don't have too but if it's sunny, why not instead of sunglasses?

I'd prefer something with less conspicuous branding however, and something I could export in a decent format. I predict this will be a somewhat mainstream gadget within 5 years (Well, for people who can afford it). Apple will make iGlasses, or some shit like that, with Siri and camera.

Then there's the whole thing about living in the moment, perhaps that's better :)