Dude, I LOVED De Niro in the film as the young Corleone. In fact, the whole movie should have been about his rise to power. Instead two thirds of it is about Michael and a bunch of lackluster characters that I couldn't possibly care less about.
You want to explain to me how I'm supposed to possibly like a movie with such an uninteresting story and annoying enemies like Pentangeli and Hymen Roth? Or the horrible twist that it was Fredo that betrayed Michael. Everything involving De Niro was great, too bad it's only about a third of the film. I hated the rest so much.
and before I saw part II, I rewatched The Godfather and I absolutely loved it all over again. My eyes never left the screen once in three hours. EVERY character in it was great, EVERY character had an important role in the story. EVERY character was memorable. During Part II, however, I constantly looked at the time wondering when the movie was going to end. It was painful watching it at one point. I think this is because I saw the first one right before. I bet if I hadn't I would have enjoyed part II just a little bit more. But as it is, compared to the first one, part II is a staggering disappointment. I will never watch that movie again.