The iPhone will support track changes through Bluetooth with iOS 4.1, currently in beta. No idea if that will be a feature functional on the 3G though.
I've had this unit with an iPhone 4 for a few days now. The Bluetooth sounds great on my end, a bit noisy to my callers. Music streaming is decent (depending on the FM in your area), but it's still an FM transmitter; there's a certain amount of hiss. As for the call announcement, I haven't had the opportunity to check that feature. My phone's at dash level in an Arkon vent mount, so I'd probably look at it regardless to see who was calling...which probably defeats the purpose of going hands free.
I'm not a heavy phone user, wanted it more for music, so it suits me fine. If I were doing more calling with it, I might consider a different product that sounded better to those on the other end of the call.
