Plus, it was a very interesting story. GF wasn't an elegantly written novel (to say the least), but Puzo was a wonderful storyteller in the great Italian tradition--and the Bocchicchio family and how they made their living was a great story. IMO, their story, and Neri's background and how the Corleones recruited him, are the best backstories in the novel.
Correct on all points TB. I thought the lamest part of the book was the Lucy Mancini in Vegas section. It just semed like filler.