I'm not sure why this is considered young adult literature. I would recommend it to the 30-somethings crowd. It does have an X-men type feel to it, but then there's the dark side that's a little too intense for young adult literature I think. The dark side is more closely related to "The Girl With the Dragon Tattoo." A little too sexually oriented and a little too dark for young adults in my mind.

Age recommendations aside, I highly recommend this series of books and I can't wait for the last book to be written.