Quality is good for iPhone use vs. Bluetooth. Sound is clear and I have less incidences of people saying I sound muffled vs. previous cars with bluetooth. Regarding A2DP, I'm not sure about that...in fact, I haven't heard of it (time to do some research).
Update- I've heard of the capability, but didn't know the official name for it. I'd bet against the current BMW model lines having this capability AND producing a high quality link/sound.
Now go and place that order!!!