For me the most appealing feature of the iWatch is the gamification of the health app. Having something that nags me to be more active would be pretty valuable to me (I think).
In an ideal world, the watch would be very smart about the context of my physical surroundings, daily schedule, time of the day, location in my home, proximity to other devices and other clues and respect my life, that would be amazing. For example, if I went to a movie theatre, it wouldn’t notify me of anything except for something very serious (e.g. your mom was in a car accident), pretty much everything else should be ignored in that location. A really clever watch would understand the context of where I was (at the office, in a meeting, in the middle of a phone call, exercising, on a walk with the dog, reading an article on the web on my computer, screwing around on the computer with a game, on Fluther or looking at stupid YouTube videos, being productive on the computer such as writing code or marketing stuff for my job, reading on my iPad, on a dinner date with my girlfriend, etc.) without me constantly having to update my status. If there was a watch that could figure this out about me and use that information to intelligently filter what is and isn’t important to bug me about that would be worth a lot to me.
It would have to completely respect my privacy and not sell my information 3rd parties. It would have to be comfortable and stylish and get a great battery life.