This movie looks hilarious, and I have a very mature twelve-year-old that has great respect for irony and odd comedy. I'm aware this film has an R rating. Would this film be okay for a mature twelve-year-old?
We all deserve to die. Even you, Mrs. Lovett, even I.
Really the only risque content is a girl who is topless for maybe thirty seconds, and a bit of cursing. I would say a twelve-year-old could probably handle it. I would advise, though, that the movie is not as "hilarious" as the cut of its trailer makes it out to be. It's a very good film, but the subject matter is slightly more dramatic than it may seem.
It's more drama with some funny bits, and when I say "drama" I mean "really really good insightful film making". I'd show it to my 12 yo. Tiny bit of nudity, but otherwise nothing a conservative prude could get upset about. Great film I though.