Well, to the people saying 16 is too young, I strongly disagree.
I'm 16 and I just devoured this book in a month and understood it perfectly. The only taxing part was the 2nd epilogue
Age makes no difference...intelligence and reading do though.
EDIT: and wow, MortalTerror. All 16-year-olds only know of malls and video games? Have you experienced the destruction of your home and uprooting of your way of life like the characters in WaP? No? Then you're no more qualified to understand the book than I am.