Drang - That is how I was going to respond too. The movement of the books is always towards revolting against the government, and the government's power in trying to put that revolt down. I would recommend them to most teenagers as long as there are competent adults around to explain that when government gets too big and too powerful, it can do the things that the government does in those books.
She kills the leader of the revolt, because she realizes that she is not that different from the government already in power. The revolution is successful in the sense that it overthrows the government, but there is still this time of unknown, when nobody really knows what the new government will do. It is an interesting way to end the books.