A few years ago, I bought a Motorola KRZR, and the kind chaps at Vodafone bundled it with a free H670 that matched the colour. At first I didn't think anything of it, but I started to use it more and more as time went on, and then I got a car and started using it even more, for a while.
First thing you notice is, it is very lightweight. That would be because it's made of cheap plastic, it feels pretty cheap, and I would be a bit miffed if I had paid for one, but for a freebie with a phone, I couldn't complain.
It has a rechargeable battery, and connects via mini USB (this was the days before micro USB took off). If I'm honest, the battery life isn't brilliant. 2 or 3 trips out and it was dead.
Call quality isn't bad, but again not great. It's fine for most applications, although in cars with a lot of wind noise, it was quite difficult for the other person to hear me. I could hear them, although the headset sounded quite tinny.
The same went for listening to music. I did briefly play with the music functions on the phone and used this rather than a pair of headphones. Obviously, you lose sound quality when playing over Bluetooth, but here it was unlistenable; very tinny, with harsh treble and no bass whatsoever. But I appreciate that this wasn't designed for listening to music.
All in all, it was a good first headset, and I was reasonably pleased with it's performance considering it was given away free with the phone, which it matched the look of. That said, would I buy one, with money? Not a chance. Plus, times have moved on in the 5 years since then, so you'll get something much better here in 2012.