I read this book a couple of years ago and it was so good that it really stuck with me. Of course, there's the obvious value of representation... I'd never read a book that address these subjects, in this setting, and I don't think I've read anything like it since.
Apart from that, the heart of the book is all about grief and loss, and not just in the form of death but also in the sense of innocence. Jay's search for his cousin, who is a perpetual child in his memory, doesn't match up with what he learns as he searches for more information, and he spends the book first trying to prove that he's right, and then ultimately trying to make sense of losing a person who is more complex than he remembers. As with a lot of my favorite YA books, the setting is young adult, but the emotions resonated with me, a bona fide adult. (Theoretically.) This is the kind of book that sticks with you, and it deserved every accolade it won and more.