This is a walkthrough of the 3 provided apps in the SDK for Android Wear. This gives a good idea of how the Android Wear will work, what it can do, and most importantly, what it can't. You won't be running apps directly onto the wear, instead developing android (iPhone?) apps that instead communicate to the devices to display content.
As far as sensors, you can be a microphone will be present, but that will probably be it. There is no keyboard option, so everything you do with the device will be voice command and interpreted.
