Really a wonderful crime. Whilst I watched the 1972 movie by Francis Ford Coppola I had my mind to read the book again (first time I read it at the age of 15-17 in Turkish).
the book shows the crime life of the post-war USA. Shaken by Mussolini the Italian and Sicilian wealthy people emigrates to the USA where they step by step form "Families", mostly mafiosi ones. But the main character Vito Corleone or the Don is described aside of this wealthy group for he's of poor family.
you can find in the book a treachery, a feud, a lot of blood-shed murders, a little blasphemy, an adultery and others of the 10 Biblical taboos (lol). but also there are much family values, good and respectful father-son relations, strong friendship, support for the poor. All this is mixed in good terms to create a masterpiece and Puzo did do it.