But what's the point of making such a character (who is ridiculously stupid and naive besides) _the_ central sacrifice in a tragedy? Sophia here or there, the character as written just wasn't compelling, her death wasn't much of a loss to the viewer. Not to mention that her story is just halfheartedly cribbed from Tony Montana's sister in Scarface. Meh.
Conflict over Anthony's career and interaction with Kay is also really absurd and vapid.
Vincent is a completely unbelievable, cardboard character who comes from nowhere.
Michael's failed redemption? What redemption? He didn't even try, he was just foolish and wishy-washy.

And yet it was not because the themes were uninteresting - on the contrary, there was so much (wasted) dramatic potential in the exploration of interaction of normal, decent people with a beloved person, who is, well, a monster. How does one cope? How do you call them to account? How does one deal with all that dark heritage, without succumbing to it? Etc.

Michael's Moses complex and view of himself as a victim of circumstances would have also been fascinating to explore, particularly if he had a real emotional connection to his criminal apprentice and sense of failure re: not being able to steer him towards respectability.

In fact, it would have been nice to see some evidence that Michael had indeed been a "good man" once. The theme of GF1 is supposed to be his fall from grace, but there is little indication that he ever had it in the first place.

Criminal plot also doesn't hang together at all, IMHO, and it's resolution made zero sense.

Nor do I see the need to have Michael "slipping", like Vito supposedly was.
Michael was clever and deadly in the previous installments, yes, but he was also lucky.
IMHO, it would have been much more powerful if in GF3 he was more cunning and subtle than ever, and almost won, but in the end luck simply wasn't with him this time.

Michael's death was also completely OoT, IMHO. He wasn't a kind of person to vegetate in despair for decades and in Sicily, of all places.
If he had been really completely shattered by the events, he would have killed himself, IMHO.

Nah, I can't agree that the film was even good. Without established iconic figures and public's emotional attachment to them, it would have been deservedly considered mediocre and forgotten by now.