My experience has been very good for colloquial English. Text messages I've sent where I've used a lot of jargon or proper names, that you wouldn't find in a dictionary, Glass understandably fails.

I shoot pool and even in a loud pool hall I can almost whisper my commands and Glass picks them up just fine. What is neat is that Auto Awesome will stitch together clips of my game, and at the end of the night I have a highlight of my match.