When the Google Glass concept debuted in June 2012, it became one of the most anticipated gadget launches ever—rivaling the first iPhone. For all intents and purposes, Project Glass, as it was then called, promised Terminator vision, a hovering overlay of information as crisp as a 25-inch HDTV. Impossible as it sounds, the product, which came out as a developer version in April, goes beyond that pledge: It's like wearing a piece of the future.
Glass is, in essence, a consumer head-up display. Incoming calls, messages, and calendar alerts pop up just above eye level. It also has a videocamera, turn-by-turn navigation, voice search, Google Now, and partner apps, including Twitter, Facebook, and The New York Times. With such a basic set of features, it would be easy to write…