5/5 without a doubt. 
 Holy shit, this beautiful, beautiful book. It makes you feel so much and I felt my poor heart hurting just as much as Connor's was. There's not much I can say without spoiling it, but with those illustrations that only gave the book even more life than Patrick Ness already created with his words through Siobhan Dowd. It was such an enticing book and I didn't expect it to be so... just so much. 
 This was so beyond words and I encourage everyone to read this book, any age, just give this a chance. 
 P.S. That author's note in the beginning brought me in before the story even began.