In GF2, we see Michael's corrupt soul for what it is, but he doesn't. He feels that he is doing what needs to be done, and he doesn't fully grasp what the consequences are. In GF3, he undertands and is trying to redeem himself. And that is a vast difference.
I dont get it... in a world such as the one he was in(to save and legitimize the family) how could he be a corrupt soul... you either play hard and make up the rules as you go or you die.
We have the hindsight and leisure to disect all of his moves, etc. He had to make them and then quickly plan the next one.
Who is to say that GF3 is really the way that Michael Corleone would have went?
I could have seen him go a similar way as in GF2. Growth, power.. conquer another industry.
