I'm just not interesting enough to need one, I don't think.
I run and cycle, but I don't really care how far, fast or high I've gone. I get messages from the same people almost every day, and whether I reply in the same moment or later on in the day, it won't matter. My job is one of great immediacy so I don't want for reminders, or schedules or deadlines. I don't travel so often that I have to keep tracks on all my tickets and check-ins.
My partner has an Android phone so we can't do the haptic emoticon thing (would I want to? Hmm). I almost never use Siri as my apps give me the particular notifications I want (not many). I also believe my Samsung phone has the ability to use the NFC wireless payment solution, should it ever become commonplace.
For £400-500, I'd far rather get a vintage analogue timepiece and use my pre-existing solutions for my digital life, none of which I feel cause me any hassle and I concede I have too many of anyway.
One of the interesting sales trends that have come from the piecemeal information that has been gleaned about the Apple Watch is that the overwhelming majority of the watches sold have been the absolute cheapest (and in my opinion, best looking) black sport model, so I wonder whether their margins on it will be relatively low.