The IMDB trivia-gatherers count 254 f-bombs in this movie.
Johnny Depp plays the late, not particularly lamented, James "Whitey" Bulger; the movie documents his rise from a small-time South Boston hoodlum to a one-man crime wave… and then his fall. There's no great moral lesson to be learned from Whitey's character arc.
On the other hand, Whitey's corruption of his boyhood pal, FBI agent John Connolly, is a moral lesson, but it's pretty straightforward: don't be corrupt.
Along the way there's a lot of unglamorous violence. Depp does a fine job of portraying Bulger as a creepy unpredictable psycho. ("Probably not that much of a stretch for him.")
Benedict Cumberbatch plays Whitey's brother, Boston politician Billy Bulger. He's fine, of course, but doesn't look a bit like Billy. (Maybe the movie producers figured they had too many potato-faced actors in the movie already.)