I do have an audio quality issue, but only with one of my two phones. The iPhone is fine, but my Galaxy Nexus is scratchy and somewhat hard to hear. It got no better with the Android 4.1 update.
It's not so much a car issue as it is the phone, because my earpiece has a similar problem with the Galaxy. Perhaps 4.2 will fix that and enable MAP protocol finally.

__________________
2011 535xi Cold, Prem 1&2, Convenience, Driver Assist, folding rear seat