Being willing to murder two people and hide away for a year in the matter of a couple scenes. I literally laughed to myself when he offered to kill the two guys at the restaurant. It was like, ok, I guess he does want in the family business...

The problem is older movies have so fewer scenes than movies of today. Much harder to tell a cohesive story that way.

I also thought Pacino was not a good choice for the role but maybe in Godfather 2 he is more believable.