The biggest complaint had more to do about aesthetics than tech. Google Glass is widely seen as geeky and fans are mocked as "glassholes."
Google thinks it has it covered. It has teamed up with Luxottica Group, which just happens to own Ray-Ban and Oakley brands and they happen to be decidedly un-geeky. Google hope to release mainstream versions of Google Glass, so it hopes Ray-Ban and Oakley could make the new products cool.
That's not all.
Google has also filed a patent for a "multi-sensor contact lens" with the USPTO. It's not exactly smart eyewear, but the lens could be a practical way of integrating sensors in a contact lens in an unobtrusive way. It should act like a normal lens, while the circuitry will be embedded outside the user's field of vision.
However, a patent application does not mean that we will see any smart contact lenses soon. They are probably years down the road, but Ray-Ban and Oakley smart glasses could be just around the corner.