This one is difficult to rate, but if you liked The Godfather, you will probably like this one, and in any case, need to read it first to get the backstory. Puzo splits the narrative here into two related story arcs. The first concerns Michael Corleone, about to return to America after his two year exile in Sicily as chronicled in The Godfather, where he is tasked by his father to pick up and return with a Sicilian 'bandit' named Guiliano. The second arc, the much larger one, chronicles Guiliano's rise from poor peasant farmer in 1943 to the most well known 'bandit' in Sicily.
First and foremost, I read this and it predecessor as an anthropological study as Puzo takes us deep into the culture of Sicily. Some may be turned off on this; Sicily is heavily patriarchal to say the least with very strict gender norms. Yet, Puzo develops the culture in many layers, moving from the outmost surface to inner core values. This is the part I liked the most. The story line itself? Good but not exceptional.
Guiliano starts this in 1943 when he, like most 'honest' Sicilians, was smuggling food to get around the war time restrictions, which mandated that all farmers sell their output to the government, who would then distribute it. The problem was the government paid the farmers in local script which was becoming worthless and then the mafia controlled the distribution, charging 50 times what the farmers were paid. So, everyone participates in the black market just to survive. In Guiliano's case, he was caught by the police with the cheese and about to be arrested when the shooting started, leaving him sorely wounded and a cop dead. Unfortunately, Guiliano left his id papers at the scene.
Hence, Guiliano had to flee to the mountains, which he did with his best buddy, and they began their life of banditry. Unlike most bandits, however, Guiliano was something of a Robinhood, only robbing, kidnapping, etc. the rich and distributing half of the take to the poor peasants. This earned him and his band undying gratitude of the poor, but as you might imagine, not the rich. Also, the mob, personified by Don Croce, the leading 'family of friends' on the island (a loose coalition of mob 'families), were not happy, as many of the rich had paid 'protection' to them were kidnapped, etc. Further, since the food distribution was controlled by the mob, Guiliano's raids were taking food from the mob's mouth so to speak.
Yet, the mob could not really disown Guiliano as he has family and friends who are 'connected'. Puzo explores the amazingly complex entanglement of the mafia in 'Rome' (e.g., legit government) as they would both love to take Guiliano down, but fear the repercussions as he is loved by the people of Sicily. Can the mob kill a hero who is feeding the poor, who the Mafia supposedly protect while they take money from the rich? The codes of honor and treachery also haunt the story, giving more insights into Sicilian culture.
I can see while people love this, but also the obverse. If you are not into a deep cultural dive, or are 'repulsed' by the culture, you will toss this across the room. If you dig this type of stuff, you will probably find it fascinating. The action? It is there in fits and starts, but more to highlight the cultural dynamics than anything else. 3.5 mobsters, rounding up!