***SPOILER***

Personally, I thought Astorre was almost too squeaky clean. Yeah, I know he was in on the hits of Don Aprile's assassins personally and all, but there was just something about the way Puzo painted him. Like he was a superhero-wiseguy or something. Slightly too unrealistic for my taste. Conversely, Aspinella seemed a little too vicious, hardly a female character trait in most of Puzo's books (or the few I've read). But overall, I liked Omerta. No, nowhere near on par with The Godfather, but still a good read. I might've just tweaked a character here and there for improvement.
(BTW, welcome Machiavelli! Excellent post!)