I'd really like to upgrade to a head unit that has bluetooth, so I can have hands free talking with my iPhone. How well do bluetooth headunits work? I want something basic. I don't listen to a lot of music in my car, so I'm not too concerned with the features. I just want it to play nice with my iphone, and if I could play my songs from my phone in the car, that would be awesome too. Does the head unit have to be actually turned on for me to get an incoming call over the speakers, or is it some kind of standby mode? Does anyone have a unit that they are happy with?