I have one so we can play with it at work. I do use the Tesla app and it's okay, although its info is always way out of date and the refresh takes forever. This is probably mostly not the apps fault--I'm guessing this has to do with the car's energy saving mode. But maybe it would be nice to have some preset refresh times so it would check to see if my car is charged by midday at work and let me know if not for example.
At the moment I'd say expensive toy, unless you have a specialized reason. I find I tire of wearing it as opposed to getting addicted. Most useful aspect is taking pictures frequently without having to stop walking or pull out your phone. I enjoy using it while somewhere like Disneyland that I'm walking around and taking lots of pictures.
I am convinced this type of thing is the future, even if we're not quite there yet. As the software improves including more applications and as we see network effects come into play with more owners we'll see more use. There's an app for tracking your runs/walks that gives some idea of the usefulness. At Disneyland it kept notifying me about past attractions (sourced from Yesterland.com) when I walked past the spot they used to be and that's pretty cool. I think that type of thing is the future. Social features when more people are on board will be attractive: e.g. a notification when a friend is near and their direction, facial recognition tied to your notes about those people, or social info about others who opt in to meet like minded people. I'm also wondering if it wouldn't be useful to see info about the restaurants or businesses in view (yelp rating, food grade etc...), etc..., but I still think that may be better handled on the smartphone where you can look at a map of a larger area.
