Mature Content, Slightly Less Mature Messages.
To start off, Elysium is just about exactly the movie I expected to see, only slightly less mature in its ideas about society. Essentially, the violent content is just about how I expected it to be, however possibly slightly more or less violent in specific scenes. In other words, as I had predicted, it was extremely gory in single scenes at a time, and in the surgery scene, it wasn't nearly as gory as I had pictured it to be. In fact, despite having watched ultra-violent movies such as Kick-Ass, RoboCop and Blade Runner, I still covered my eyes in some scenes, such as when a grenade explodes and a man's face is half-blown off, eyeball, skin and everything (or at least I tried to, and did so later when they showed his face again), and when Max's (Matt Damon) surgery begins. So, in conclusion, if you're worried about the violence in the film, then I'd recommend the film to a 13 year old, as long as they they are mature, and they cover your eyes in select scenes.
In terms of the quality of the actual movie, it was worth watching at best. The cinematography was mixed, in that some shots were great, but the shaky cam technique was used in excess, not that I love it being used at all. I felt that it took away from much of the beautiful special effects that should have been viewed in all of its glory. To be fair, this was mostly disappointing because in fact, the special effects were amazing, especially when viewed without the shaky cam technique. As for the story, it was touching at times, but derivative mostly, as it made out ALL wealthy people just to be power-hungry elitist heartless people, when in reality just because someone has wealth doesn't mean they refuse to share it with the poor, and it certainly doesn't make them ruthless and vicious (which were the two describing words of Jodie Foster's one note character). So, all in all, Elysium is a gritty, violent, somewhat simplified and epic movie that is worth viewing at least once, especially for sci-fi fans.
What other families should know
Too much violence
Too much swearing