If your kids have played the video game, they will definitely be fine with this film. The game was very morbid and violent, but also fairly smart in terms of social-commentary and hillarious at times. The movie does have violence but is not as bad as the game, however the movie is fairly faithful in terms of humor. Anyway, it has pretty much everything that is objectional, however I think most mature teens can handle it.
Let me just say that if you think that this movie would teach your kids to go off and set things on fire or shoot people in the streets. You have a hell of a lot more problems than an R-rated movie. Yes, this movie has over the top violence, enormous amounts of profanity, constant drug usage and references, as well as full-frontal male and female nudity, but that's what makes this movie stand out. Sure, most families will say that it's highly innappropriate for kids; but that's because THIS MOVIE ISN'T FOR KIDS. That's why it's rated R. The MPAA didn't rate this movie PG so that kids could go see Verne Troyer being molested by primates in one of the character's basement. Grow a brain and don't buy this movie for your kid just so that you can complain about it later unless they're mature enough to handle this.