Plot, plot, plot. Our heroes win and save the day and then magic goes away. I don't care whether it's Tolkien, Mary Poppins or Gaiman, I hate hate hate that ending. It's at its most egregious when it is tied to children growing up and magic is only for innocent children. I can love the rest of a book but that ending is going to make me not want to read it again. I've repeatedly described The Graveyard Book as 7/8ths of a truly great book.