Used one yesterday. It's tiny, the 38mm one. I would get the bigger one for sure. Not sure about the whole wearing a watch thing though.
I've got the 42mm one, which I think is just right. I bought it for the longer batter life more than anything, but I'm happy I got that size. This is the first time I've worn a watch in about 6 years, and I have to say the
I bought it basically because I didn't understand what the point was, and I wanted to see if it was compelling. After 5 days, I think it's basically a good product and I will continue to enjoy using it. On the other hand, it's clearly a 1.0 product and has some rough spots. 3rd party apps are slow and sometimes don't open correctly at all (they run on the phone for now and just display on the watch by sending stuff over bluetooth). I think that will get better with the native SDK being announced at WWDC this week though. I really like the exercise functions, and it's definitely making me get more exercise so I can fill up my goal circles.