I have the Parrot 3200 LS-Color handsfree car kit on mine. I absolutely love it.
Ya don't have to link up to it every time you get in the car. It does it on it's own. It mutes the stereo or pauses my cd, whichever is playing, and the sound comes through my stereo speakers.
It tells me who is calling with my voice recognition, shows me their picture, tells me the number and the name of the person calling. If the person is not in your address book, it shows their number.
No matter how loud I have the stereo, I never miss a call. The sound is clear both ways. I don't have to talk loud to be heard. The passenger in my ST can talk calmly and still be heard.