[Pewpewarrows]

What's the difference between them offering snap-on Glass over existing prescription glasses, and offering an existing Glass model with snap-in prescription lenses? You need to have one or the other, and in both cases it's an addition to normal glasses, not a replacement. Your requirement can never be satisfied for those with sub-par vision.

As for your main point: for this initial model, the main benefit it offers, that I hear from users time and time again, is the instant photo/video capability. Not having to dig your phone or camera out of your pocket / handbag is a huge win for a lot of people in the initial explorer program.

But that's not why I think the product will succeed. I can see the future potential of an always-on heads-up display, and that's just too useful to pass up. Will it ever get there? Maybe not, but I think it has a greater chance of that than failure.