I just finished my first reading of the book and I think the movie was much better.

Keep in mind I have watched the movies (part 1 and 2, but not 3) several times, so maybe my judgement is clouded.

The book, aside from the last two chapters, is pulp fiction. The dialogue is stilted and unconvincing. The sex scenes were tawdry, more suitable for a bodice-ripper romance. The side stories with Johnny Fontane, Luci and Niccolo (?) were a waste of ink.

The don in the book was a 2 dimensional cartoon character; Brando made Vito flesh and blood.

The book was a good read, but it's something I'll have forgotten by tomorrow. The movie, by contrast, is a monument in film, an experience you can never forget.

Normally I like the books better than the film versions. But not this time.