Honestly, if I'm walking down the street and I see a cop, I tend to ... behave ... better. (Not that I go around looking for trouble or anything.) If there's a cop watching, it doesn't really matter to me whether or not he's got a camera on his glasses; either way, I'm being watched.
If this cuts down on police abuse (and other wasteful crap), then I'd say the pluses outweigh the minuses.