I read the book first as many people probably did. It was a good job overall. However, they did not convey a big plot in the movie that they were also battling the elements to prevent them from dying of natural causes/exposure. There was the big struggle to find water in the book and in the movie it just seemed readily available and no problem. They pretty much focused on the kids hacking away at each other. Which is a warning to parents because I saw a dad with two younger boys in the theater, and it was super-violent and not appropriate- even if they have read the book. I was proud of all the teens in theater, at first during previews they were super loud, but once the show started they were focused and became very emotional during the film. I saw how they related to the teens so the movie does a good job in that respect-enjoy!