Several years ago Bank of America sold my mortgage to M&T Mortgage. I haven't had a single bad experience with my mortgage since. (Which was the exact opposite of all of the terrible experiences I had when BoA held my mortgage.)
Most recently, I found out from M&T that my insurance policy had been cancelled. I faxed my new insurance docs and called to verify everything was in order. It was one of the most pleasant costumer service experiences I've had with any company, not just mortgage.