"Keep your friends close, but your enemies closer."
The Godfather Part II
Usually with sequels -- it's either bad or better than its predecessor. But that's not the case as The Godfather Part II is on par with Part I, most thanks to the brilliance of Robert De Niro who did a superb job playing a young up and coming Vito Corleone.
Also, Al Pacino was incredible, (although he was over shadowed by Marlon Brando in Part I), his character mature on-screen beautifully -- shame the Academy Awards had to pass on him for Best Actor.