Interference seems to be a big problem with Bluetooth. There are certain intersections in my city where the signal craps out while crossing the street; certain sections of the train and bus routes, and other places where music simply stutters or dies. I assume there's a local point source of interference to blame in each of those areas. I ended up fixing the problem by shelving my collection of Bluetooth headphones and going back to using wired headphones. The sound quality and reliability are far superior, and the wire just isn't a problem. I'm also not careless enough to ever have dropped my phone in water, so that's never been a real issue for me, either.
So while Apple said "everybody just use Bluetooth", it was obvious they never have. I'll be hanging on to my older iPhone for quite a while yet.