As cool as the idea sounds, I'm sceptical of the real life usage scenarios. It would be interesting for the first few days, but after that I think it would be simply annoying. Just think about getting notifications from FB, Twitter and other apps all the time - with mobile phone you can just ignore them and check later when you have time, with Google Glass they would be thrown right in your face. Not to mention ads, which I'm pretty sure will come sooner or later, and I won't even start about the privacy. Also, watching the Google Glass ad[1] I was constantly switching my focus between the display and the actual view - in real life it's a great way to have an accident. And one last thing, from the ad I've got the impression that the main use case is sharing your life with others, which I think is already at ridiculous level (like people sharing what they ate for dinner) - now it'll be even more ridiculous by people showing off they entire day (me walking in shopping center, me riding on a bike, me eating and so on).
I agree with your sentiment. Privacy and ads are a huge issue for me (and the reason I will not own one).
As far as usage cases, I can see this being extremely useful while driving, if it's not too distracting. If it silently records and uploads everything while driving, it just became an internet-enabled dashcam. It's also a customizable, interactive HUD. While it's already used in the military (airplanes, helicopter helmets), I can see a case for ground troops having these (real time tracking, enemy location marking, aiming assistance, etc).
I also believe that it's not going to be a always-wear scenario. I think it's going to become a bluetooth-earpiece use case, i.e. wear it when you need it, put it away when you don't. If you recall, people used to wear those earpieces everywhere when they first came out, now: not so much.
At the end of the day, it's cool technology and potentially extremely useful. But it's created by a company whose core business is collecting data and selling ads, and the idea of embedding themselves into EVERY facet of my life is extremely unnerving.
"Privacy and ads are a huge issue for me (and the reason I will not own one)"
Has there been any indication this product will have ads? It is a paid product, unlike Google services. Google's products so far haven't had any ads in them.
You are right, there is no indication it will have ads. But just because it's a paid product does not mean that the cost of the hardware cannot be subsidized by ads/data, or will not be in the future.
Either way, as I stated above, data and ads are Google's primary business model. It is more a (perhaps-irrational) distrust of Google having the potential to use my data, than of the concept itself.
I don't mean to single out Google -- they are generally good with non-intrusive ads in GMail and have a proven track record of security. But it freaks me out that any company would have access to everything I see.
Also what happens to all that data when the terms of service are changed (like ToS was changed last year)?
Seems like you're less likely to have an accident if your GPS directions are right there in your field of vision than if you have to look away from the road at a device on your dashboard or in your hand.
[1] http://www.youtube.com/watch?v=v1uyQZNg2vE