I have the BackBeat for my iPhone (holding out for a 3G iPad). I love it because I can listen to stereo music, interrupt for a phone call, and then back to music all invisibly. I have long hair so you cannot see that I have anything on. It is comfortable to wear and you can leave it in with no music or phone call and still hear and talk to people around you since it doesn't completely block your ear canal. Sometimes the back of the neck wire bumps your shirt collar but you can shrug it to the inside easily.
The iPhone doesn't have full bluetooth capability though so you cannot skip tracks, only start and stop the music. I don't know if it's a defect in mine but I cannot change volume either. I can initiate a voice dialed call so it's great in the car (no tunes, just waiting for a phone call).