If the Apple Watch is the original iPod, then I'm waiting for the iPod Shuffle of smartwatches. Something inexpensive with great battery life and an interface so simple it doesn't even need a screen. Just like the iPod Shuffle made me realize there was a place for a small and simple device that didn't store one's entire music library, I don't need to launch apps or send doodles from my wrist. I would like to track my movement, sleep, and heart rate though. I would like to get a light buzz when I receive a notification, even better if I can select which apps send notifications to my wrist. I would be interested in using a wrist-worn device with Apple Pay or to unlock my Mac. Maybe it could also be used for basic controls like the Apple headset is (pausing/playing music, answering/ending calls, activating Siri, etc) . The Shuffle also greatly improved on the iPod's battery life. I anticipate the Apple Watch will need to be charged daily. A simple wristband without an LCD screen could last several days on a charge. Of course, it would also be less expensive and could come in several different colors.
I'm trying to reserve judgement on the Apple Watch until I get to personally use one, but I just don't see what it does that my iPhone can't (there are a few though, such as the remote iPhone camera viewfinder, which is pretty cool). A Jawbone Up is a simpler, less expensive, and more appealing option to me for the time being.