The Fortunate Pilgrim

I am supprised that no one else has discussed this book in the past 45 days. It is Mario Puzo's favorite book. I had some questions. This is said to be a novelization of his life. I did find coincidences to his discription of his life in, I believe, the Godfather Papers. But how parallel is it to his vita? Was his older brother really involved in a local Mafia? Did his other brother died in a tragic rail road accident? I did read that he did join the Army. Anyways, would somebody, who KNOWS, tell me how true is this incredibly dark and interesting novel is?