I went and did the Apple demo. I was there for something else at the time, and they had an opening, so I jumped on it. I highly recommend doing the demo, it’s honestly really freaking impressive. I’m not positive what the killer app is for it yet, or if this is just a step in long term AR/MR, but what they’ve done is really impressive. Yes, it’s expensive as hell, and my suspicion is that long term the displays will be replaced with a waveguide (Stanford’s looks pretty good at this point), so it won’t need the external-facing display, but they’ve got the head and hand-tracking in a good spot, as well as the gestures needed for it.
Maybe, the killer app will be the overlay itself, where it uses a camera/location/audio to see what’s going on and present more context. Looking at a menu? Okay, I’ve had this and this and liked it, but their X I’m not a fan of. I need Y from the grocery store, where is it on the shelves… more than anything, I think that they saw what Google glass could become capable of, and thought that the phone as it is now (screen, etc) was going to become obsolete at some point, and they were terrified of losing that race.