Absolutely right, its unbelievable how many great films come from the mafia genre. I'm a big Cagney fan, and I think it all comes from him. Modern mafia films are also massively influenced by fifties American noir films like Double Indemnity. The Sopranos and Boardwalk Empire deserve a mention as boxsets. Gomorrah is a different take on the genre. And never really gets a mention but Carlitos Way is right up there with the best of them too.