What's so great about the godfather?

People always rave about how The Godfather is the greatest film ever made. What? The film sucked. So many problems. First off. no plot. No character development. The "action" scenes sucked ***. The film was ridiculously slow and boring as hell. The acting was horrible. The scene where Sonny beats up that other guy was one of the worst scenes that I've ever seen in my life. It was so obvious that he wasn't actually hitting him. Then we get a stupid ending with a bunch of stupid characters that I didn't care about. What was so great about it?