Just finished reading it the other day - like most of Puzo's work, it's engaging, enjoyable trash. Nothing wrong with that.
The only novel I've read of his that really stands out as literature is The Sicilian.

It was kind of irritating to find the occasional grammatical mistake in The Last Don, or silly mangling of phrases - "illusions of grandeur" was almost on the "for all intensive purposes" level. Sure, anyone can make mistakes (just look at any internet forum), but an established writer? Not to mention whoever edited the book.

That's just quibbling though, I did enjoy it. Main problem seems to be that it's on far too epic a scale for a story with so little real substance, much like the big, dumb Hollywood films Puzo seems to be commenting on in the novel.

Will track down the TV adaptation, I imagine the brutality with which novels are treated by screenwriters could work wonders for this one. Sure did for another sprawling Mob soap opera Puzo chucked together a while back.