The link below gets you to a review by a younger reader which is worth a look. Meanwhile off to library tomorrow to seek out the next 2-be better prepared next time!
http://www.theguardian.com/childrens-books-site/2012/jul/29/review-knife-never-letting-go-patrick-ness
PS I thought the quote above from Patrick Ness himself rather good :-) Going right from adulthood back down into schools...quiet folk have stuff to say too, they might not want to be right at the front saying it though.