It'll be interesting, but I don't think that this kind of product is going to replicate the success of the iPhone, because, in my opinion, the form factor only comes into its own for fitness fanatics.
The size restrictions of a human wrist means that a watch is always going to be restricted in screen size, and because of this, a watch can only ever really only show you a considerably smaller subset of information than your iPhone, and so the utility of it is limited compared to an iPhone.
If you're just walking along casually, an iWatch is surely just an unnecessary duplication of functionality since it's just as easy to leisurely pull an iPhone out of your pocket, than it is to move your arm up to your face to read a watch.
So, I only see it making sense for fitness scenarios where the form factor means they can strap the device securely to themselves. I think that most people use their phone to tell the time now and have moved on from traditional wristwatches. I haven't worn a watch for at least 10 years.
