While the movie stays true to the book, it ends up changing the moral of the book. Where in the book Juli stands up for herself and realizes that Bryce needs to stop hurting her feelings, the movie makes it to where after all the times Bryce hurts her she still ends up falling for him at the end. So the whole moral of letting people treat you with respect in the book is just gone in the movie. Aside from that the movie does stay true to lots of the events in the book.