Denzel and Russell should make for a classic right? There's really nothing wrong with the movie but there's definitely a lack of energy about the whole thing. Scenes taken individually are well constructed but nothing held together and at times it was almost boring. The best thing about the film is that it's based on a true story and you can research the real Frank Lucas afterwards. here's "The Return of Superfly," the article that got the ball rolling on the movie.
Compared to something like Heat, American Gangster had nothing to recommend it.