I've been a customer of American Express for many years. First with a Gold card and then I got my Blue. I always turned down the Platinum because I didn't need it and eventually closed my Gold card so I now have only the Blue card.
My credit rating is excellent and definitely better than the average person so that may be part of the reason I get a very reasonable rate. They even reduced my interest rate a couple of times without mentioning it.
American Express representatives have called me asking about certain charges and recently there were a few small charges that I knew nothing about. They removed those charges and sent me a new card quickly. There was another time when I had a problem with a company and they removed the charge for me.
The closest I ever had to a problem was years ago when I received a letter stating that my payment was late. It was actually made two weeks ahead of time. I called and the rep confirmed this. Seems to have been a computer glitch and the computer sent the letter out. It was cleared up within three minutes.
American Express has never given me any real problems and always friendly customer service. I expect to remain a member for many years.