As someone who has actually used Google Glass, the camera/videocamera was the very best part about it. The killer app for me (and others that I knew) was taking photos/videos of their kids. My daughter knew what I was doing when I pulled out my phone (and often wanted to take it from me), but she didn't know what to make of Glass and so I got a ton of great candid photos/videos of her.

That said, I was always VERY self-conscious wearing Glass, which doomed the experience for me for the most part.