Yeah, that's a bad idea. If I was to be able to get someone using that thing to disengage, given that it is attatched to their wrist and dangling there, it's going to help me break their arm. And like Drac said, there are other much more practical things that can be done from that range that cost less.
It's kitschy, but impractical IMHO.
BTW, look at the picture. You could be using his shirt to choke him if you wanted to choke him, you don't need a fancy watchband. That way, you can use your wristspace for gold, thus enhancing your style.
I'm not actually using it the way I'm supposed to be using it -- the picture was taken for comic effect. The theory behind the band is that it's easier to apply a vascular choke with some sort of artificial leverage than with just your limbs. I don't expect I'll ever use my review sample, but it makes a nice watchband and I'd rather have it than not have it.
I view items like this in the same way as credit-card knives, weighted bandanas, and any of the other improvised/backup weapons people carry. It's not going to be my first choice but as others have said, better to have it and not need it than need it and not have it.
The best weapon is the one that gets the job done.