Well, if you did, you missed the whole point of the movie. The two previous films were about Michael's journey from innocuous third son to the pinnacle of a crime empire, the evolution of his character, the revelation of his true self. III was about his catharcis, epiphiny, regrets, the reconciliation of his fratricide and his million other sins with the path not taken.

You skimmed the film's surface. Watch it a couple more times.