I am a glasses wearer that drives a lot (25k miles per year), cycles a decent amount (around 1,000 miles per year), plays sports and practices a martial art - I am constantly dealing with blind spots caused by bridges, nose-pad temples, as well as reflections off the lenses. Unless Glass becomes significantly smaller (it will get smaller over time, but I'm talking a few cubic mm) it becomes one more blind spot.
Certainly for me it would become enough of a hassle that I couldn't imagine wearing it around all the time, which means having to dig it out for the times when I do want to use it (which means remembering to bring, etc) - at that point, why not just use my cellphone?
I suspect I'm not alone, but we'll find out over the coming years.
Slightly off-topic but I always liked this concept: http://www.coroflot.com/billymay/Nike-Hindsight There's plenty of room for Google to innovate in glasses design if they're willing to throw away people's expectations of glasses-as-fashion.
My brain edits that sort of stuff out. In fact my current pair of glasses is frameless; there are some nuts holding the node-bridge to the lenses that I saw ALL THE TIME in the first few weeks of having them, but now never really see at all unless I'm explicitly thinking about them. Like now.
I would LOVE to be able to do things like summon up maps displays without having to look down at my phone.
