A worldly 15-16 that loves great theatre and can appreciate satire.Lots of blood and sexuality but done with intelligence and artistically awesome . It's an amazing show. My 16 year old daughter is a budding actor it is her favorite show of the season (and also one of mine- I'm in my 50's).
Thank you for your responses everyone. I'll have to think about it, but I think the 15 year old I know is mature enough. PThespian is right, it really does depend on the child.
Honestly, I was shocked by the number of teens I saw at the show. It is definitely a show for them - a few were actually crying at the stage door the other night and telling the actors how the show changed their lives.