I agree totally with Don Rico and Sonny. The book is really good. I only read it because my dad wouldn't rent me the movies, and after I read the book my dad realized that a book can be more graphic and descriptive than a movie can be, so he caved in and rented them for me - I was 12 at the time. Now The Godfather is my favourite book of all time and I managed to convince my Literature teacher to let us study it in class next year.
I highly recommend the book, if you liked the movies then you'll love the book, as a lot of the character's speech is the same and having seen the movie you can picture the actors while you're reading which I think adds to the effect.
It's definately a book worth reading.
Liz.