SPOILER WARNING!!!!!
I didn't find as much if a problem with Winegardner's writing as I did with the UNDOING of "facts" that we've known from the book and movies.
Michael went to Dartmouth.... Kay had an abortion...Fredo struck a deal with Rith because he was more ambitious than smart, not because he was manipulated. These are things we KNOW....I found Winegardner's boldness in rewriting Puzo (and Coppola) unpalatable...It was his job to fill in the blanks, not change the characters. If Michael had Dr Jules killed for performing an abortion on Kay, and that abortion never happened, it not only is a statement on Michael's brutality, but his ability to find out the truth as well. The same goes for Michael's killing Fredo, rather than preventing him from being manipulated by a more cunning rival. That changes what know about Michael from before. I don't know about all of you, but I was interested in seeing an evolution of characters, not a rewriting of them....