directed by Scott Cooper
This is a horror film masquerading as a gangster movie. I don't mean that it does so because of the explicit violence. Compared to some Tarantino and maybe even Scorsese films this movie is not all that explicit.
Of course that said I am likely a little inured to cinematic mayhem so maybe you should take that last statement with several grains of salt. When I compare this to a horror film I mean that Johnny Depp, portraying pitiless South Boston Irish-American gangster James "Whitey" Bulger, does masterful work depicting the soulless cold black hole of a human being that Bulger was during his days of dominion over Boston. Bulger is less a human being than a ghoul. He's something almost unnatural. Depp's Bulger kills at will from cold calculation.
He inspires others to kill, often out of pure fear. If nothing else Depp's version of Bulger will put you in mind of Nosferatu. His Bulger is all bulging forehead, bad teeth, stringy hair and arctic blue eyes. He's a predator of other humans. His gravelly voice commands, insults and frightens. Bulger is rarely kind to anyone other than his aged mother, sickly son, brother and less occasionally his wife. Everyone else he regards as someone to be ignored, used or consumed. When Bulger loses two people close to him he sheds all but a thin veneer of humanity.