I wasn't sure what to rate this book, because there were parts I loved, and parts that felt like a chore to read. I loved the central premise, loved the geeky references and the general plot. I also loved Art3mis and Aech as characters. At some points of the book (usually the parts about actually finding the keys and clearing the gates) I could not put the book down, particularly towards the end. 
 However, the points in between I often found myself bored and skim-reading. It seemed like it spent a long time explaining some things which really didn't need to be explained at all, and was guilty of more than a few info-dumps. Furthermore, I wasn't really sure what to think of Wade/Parzival. I alternated between finding him a bit irritating, to finding him boring and stereotypical (although this is slightly hypocritical, as I loved Art3mis who is basically a walking stereotype). Particularly in the middle of the book, Wade spends a lot of time moping about feeling sorry for himself, which I understand is in contrast to his character development at the end, but really we didn't need to hear all of his moping. 
 All in all though, I enjoyed this book, although I think it could have been executed better.