I personally dont like them. I think cell phones in general are rude. I carry a cell phone but it's turned off. So many people walk around too involved in their telephone conversation that they are clueless to their surroundings and their enviornment.
The whole blue tooth thing is a bit much in my opinion. There isn't anything that is so important that requires me to always be instantly available. Although I think that if you must talk while driving that hands free is the way to go. I would much rather see someone driving and talking using blue tooth than a hand held phone. But please, when you get to your destination, take the thing out of your ear. It just looks like your trying to be self important.