I read about a third of it, then skimmed the rest ... obviously it was a lot of work to write, but it didn't work for me.

First of all, it tried too hard to create artificial "connections" with people we had never met before. Too many mystery illegitimate kids, half-cousins, long-lost relatives from Italy ... ack. Too much.

Then, for all that work which went into introducing all these brothers and cousins and so on, there was no connection - other than Vincent Corleone - with anybody from the previous three episodes. No Al Neri as a senior consigliere in his 70s. No Johnny Fontane as a grand old man of Vegas or Hollywood. No Aunt Connie acting as the "Black Widow" of the entire family. No Grace Hamilton from Ep. 3. Just a bunch of people with familiar-sounding names that you have to explain why they're there.

It also really really overdid multiple rehashes of the semi-incestuous overtones of GFIII -- seriously people it is not really normal to be hot for your cousins or half-cousins. I can see it happening on rare occasions but in this script it's all over the place. Every time somebody meets their long-lost illegitimate cousin or sister or whatever they start acting hot for each other. Eccch.

There were some excerpts which read OK and could possibly be adapted into a revised script. But I'd advise to go back and cut the number of characters about in half, radically trim down the number of branches of the family tree, bring back a few familiar characters from GF III for continuity, and try again.