I've been thinking a lot about the Mirror API today and I came to a conclusion: the API is really only useful if you fall into one of the two following groups.
A. You have a pre-existing site or service with users signed up, and you want to be able to let those users get notifications if/when they get a Glass set. The most obvious example is something like Twitter, who might want to post a card to your Glass when you get an @reply or DM.
B. You have a massive backend infrastructure that can do things like analyze people's faces or color-code a building you're looking for, or other types of augmented reality activities.
There's not much else to do with this API otherwise since it just boils down to sending messages to a user's Glass and occasionally getting a response if they choose a menu option. What's a little troubling to me is that even if Glass were completely opened up, this wouldn't really change. Smartphones are great because anyone can build something nice and simple from scratch. If I wanted I could make a Pinterest or Instagram clone with my own "spin," or any other kind of trivial idea that pops into my head that wouldn't necessarily make any money or set the world on fire, but would just be rewarding to make and get other people to use.
With Glass, right now or even perhaps in the future, that kind of thing is impossible. And even worse, the most "Glass-like" services are already, or will likely eventually, be bundled into the operating system by Google themselves. Stuff like turn-by-turn navigation, getting answers to simple questions (search), photo and video capture, livestreaming and video chat (hangouts), and mail and text notifications are built-in by default.
Eventually I think it will probably boil down to only Glassware of Group A will be viable, and what's truly bad about that is Group A Glassware exists as only a companion to more powerful, functional, and versatile apps and sites. This means there will be few, if any, Glass-exclusive apps, and Glass itself will only be a companion to phones. This isn't shocking when I say it as such, but I think many people imagined Glass being a bit more versatile. I personally thought that a few revisions down the line it could make for a good smartphone replacement (especially if you have a tablet), but now I'm doubting that could ever be the case.
This is a bad outlook for third-party app developers, and it's not even really Google's fault. You could blame them for the limited API and absorbing app opportunities into the OS itself, but that's beside the underlying problem, I think. Interaction with Glass is inherently limited, and that limits the types of apps and developers that can develop for it in the first place. (In this sense, the limited Mirror API makes total sense.) There's voice gestures, a single "up" head gesture, and the touch pad on the side, but all of those are extremely clunky to use -- especially in public. Honestly, I would really rather have a small, single-hand d-pad or something (imagine the size of a keychain car starter) so that I can use Glass on the subway without looking and sounding like (more) of a lunatic or tiring my arm out by holding it up to the side of my face the whole time.
The only real hope I have to resolve this is eye-tracking, but I'm unsure how viable that is considering everything else about the device. Like color e-ink, it might be the endlessly-delayed factor in me getting into Glass.
I'm excited about Glass, but now it's the kind of excitement I feel at the release of a new game system, and not necessarily the kind of excitement one would feel about an entirely new and transformative user interface paradigm.
