How much of your field of vision does it generally take up? If I catch someone using it when we're ostensibly having a conversation, will I be able to sucker punch them with impunity?
Not too much, only the top right corner. And why are the sucker punches limited to just Glass? Why not someone who stares at their phone during a conversation?
Do any of these apps overlay information into your field of vision/hearing about what you are looking at? If so, how is the performance (is it real time or laggy?), and is it distracting?
Yeah there are a few apps (well, web services known as "Glassware") already. I haven't played with too many of them yet.
None of the third party apps are overlaying information in an augmented reality fashion. The performance is pretty good, the navigation maps turn smoothly when you turn, etc.
It is a little distracting, but not nearly as distracting as I was expecting.
I am keen to read while driving on an autobahn, is it save? Can I develop while looking out of the window? That would be great, this staring on a screen always felt somewhat autistic.
Yep it has, since it's tethered to my Nexus 4 for data when not on Wifi. Plenty still works without data, you can still take photos, browse the "cards" that are on the device, etc.