In the LRB:
In American Gangster the plot doesn’t stagnate but it does go soft, and this is where Scott loses control of his balancing act, where the fantasy of self forgets about the social reality, and Denzel Washington escapes into pure charm. He grins like his old screen image, and the hard fierce face he has been displaying disappears completely. Crowe, similarly, whose character has now, through diligent hours at night school, become a lawyer, abandons all his anger about the drug trade and smiles in sheer admiration of Lucas’s resilience and ingenuity. We are told that Roberts, as a lawyer, became a defence attorney and represented . . . Frank Lucas. It was a buddy movie all along.
Part of what is happening here has to do with race and class politics. The stern black Lucas and the driven working-class Roberts are different from everyone else: the corrupt cops, the time-serving government officials, the doped-up soldiers, the Italian gangsters. They are different not because they are honest (in their way) but because they are scorned and they are rocking the boat.