It's worth seeing if only for the performance of Raf Vallone.

Rating: 7/10 (10 October 2004)

Al Pacino is, well....Al Pacino. He delivers his usual exemplary performance in this one. George Hamilton, despite the fact that he is often savaged by critics as an ageing pretty boy, is quite credible in this film as the urbane topnotch corporate lawyer helping Michael get out of the bloody Mafia business by acquiring legitimate and respectable holdings.
But the real gem in the movie is the Italian actor, Raf Vallone. Often cast as a "heavy," a Mafia enforcer in countless gangster movies such as in the original Italian Job (with Michael Caine), it is refreshing to see him cast in a sympathetic role. As the Catholic Bishop of the diocese covering Sicily, he becomes father confessor to Don Michael Corleone and offers him saintly advice. His character is based loosely on the short-reigned John Paul I (Albini), a theologian, philosopher, essayist and poet of high caliber.
I will never forget his observation on why the corrupt Mafia culture persists in Sicily. He pointed out the stones in a stream/fountain in his courtyard. Then seizing one, he smashes it open to reveal that its core is dry. These people (the Mafia), he says, are like the stones immersed in water for centuries. They have been Christians for hundreds of years but they have never absorbed the true essence of the faith.
I liked III better than II which I found ponderous and filled with sympathetic yet corny details especially on how Corleone Sr. rose from petty mulcter to a leading Mafia Don. He was just evil, period.