iPhone and BLuetooth head phones

first off, i want to clarify that i am asking about bluetooth headphones for music, not a bluetooth earpiece for talking...

has anyone ever used bluetooth headphones to listen to music on their iPhone? i am thinking about getting some, i just joined a gym, and want to listen to my music without the hassles of a cord. in case you aren't familiar with that i am talking about, here is a link to see a set Newegg.com - Motorola Behind-the-Neck Bluetooth Stereo Headset Black (S9 Black on Black)
i haven't decided what kind to purchase, that's just an example. i just wanted to know if anyone has used them and had any opinions.

I've been using the Motorola S9 headphones since Black Friday ($49.99 @ Best Buy) and love 'em. They sound great, have a great range and battery life is pretty good too. I use them on my iPhone 4, MacBook Pro & up till June 24th my 3GS. If a phone call comes in while you're using them they work as a bluetooth for phone calls too.