1. It's just plain-old gorgeously written -- passionate, hilarious, moving, thought-provoking, character-driven, with solid values (though, granted, it would be nice if every single teen in it wasn't constantly puffing away like little nicotine fiends -- have we really not gotten past that as a way of showing cool?).
2. Unlike most books of this type, every single adult in it is warm, caring, and intelligent: the parents, the teachers, the local cop -- even the requisite rigid disciplinarian who enforces the rules at school is not clueless, has a sense of humor, and cares deeply about the students.
3. The characters are vividly real, complex, and beautifully drawn. Miles, the narrator, is painfully truthful, sardonic, yet sweetly naive. The Colonel is the kind of friend who understands friendship, and the ins and outs of high-school society. And Alaska is just hilariously charming -- the reader will be almost as in love with her as most of the characters are.

For a novel with very little actual plot, this is a hard one to put down. Since new chapters don't start on a new page, there's always a temptation to read just a little bit further and, for the first half at least, you'll do so grinning all the way.