First and foremost, welcome.
Sometimes it takes a while to get replies. Who can say why? In this instance it might be because lots of people think the premise is so obvious as to not be worth discussing or has been discussed over and over again. Or maybe board activity is just at a temporary low tide. But again that's just a guess. It is always good to have people with contrary opinions here.
I can tell you my opinions. I was interested in the books when they came out but upon reading lost interest. I simply didn't think the writing style was very good. I didn't need the Fredo being a closeted homosexual theme as an explanation for his angst and "weakness". I considered that really lazy writing. I thought the names of some of the other mobsters were cartoonish and Tom getting involved in hits pretty outside of his character. I had zero interest in the lives of Sonny's children.
But fundamentally for all of the flaws, repetitive themes, weird obsessions and poorly written sections of Puzo's novels they were HIS novels. Winegartner's versions read like rushed fan fiction. And I'm not a fan of fan fiction. It's like sitting down to read a Conan story and discovering it was written by L. Sprague DeCamp or Lin Carter and not Robert E. Howard. Yeah, the names are the same and the structure recognizable but the spark is gone.
I would almost be more impressed if Winegartner had just written his own story of Cleveland or Midwest mobs and just included a few teaser references to the Corleone or Barzini Families back east. That certainly seems to be where his primary interests lay.