I think that half the fun was that it was so unexpected. We had put off watching it for a while because we had expected a crappy B movie. It is hard to find good funny movies as sense of humor varies with location and time.
Some movies that we thought funny in the Fifties and Sixties seem quite dreary nowadays. Part of the problem is that the good movies of the past have been copied so many times the the jokes and plot themes are no longer new.