Depends on the watch
Having a nice watch on the wrist is convenient for a quick time check, more so than picking up my phone. Ditto, in other circumstances having a tough old watch that doesn't mind a few knocks, that I can risk getting scratched etc. if I'm doing a bit of gardening, tidying, cooking, other messy work.
If I could have such a watch that would also pass me my messages I'd be pleased and might even get one. GPS could be useful to me too if it was made practical, since it saves holding the phone in my hand. I'm a bit puzzled by the fitness app thing. Yes there are plenty of joggers. But really are there that many fitness fanatics around?
As to any other "smart" features; what's the point? If you want to do BookFace/Twitting and so on you are going to spend long enough to make it worthwhile to pick up your mobile with a decent screen.