Mixed results when driving on the freeway in my small car. In all cases, I'm referring to the same situation, freeway, same speed, similar weather, same car.
Sometimes the call quality is very good (for the other party) and sometimes it is bad (where I'm told that it sounds like very heavy rain hitting my windshield). Not as bad as my originals, but not much better either. At other times, it is quite a bit better. When it's good, it's still obvious that I'm driving, but not a hindrance.
Had the left earbud cut off yesterday with occasional loud crackling sound that was almost painful. Was fixed after I put them back in the case and called the person again. Not sure if this can be fixed by software or if it is a production fault. I'll contact Apple about it if it happens again. I'm sure some things will be fixed with software updates.
Hope this helps