Yeah, it's not really "teen adventure" it just so happens that the main character is a teenage girl... it's really post-apoc sci-fi/adventure more than anything... it's not like the books were written in a specific way to appeal to teens imo.
I've read the books and they were worth the time... I did feel like all three kind of ended weirdly... books are always better than their movie adaptations as far as I've ever seen.
I borrowed the first book from a friend. Hopefully going to start it this evening.