it was a pretty good movie ON ITS OWN. but its nothing alike to the book. for starters, the entire conflict in the book was to run to a save point FOR wicked, but in the movie they're running AWAY from wicked. which messed up the rest of the major plot points, like the entirety of group b kidnapping thomas and teresas betrayal. speaking of group b, there was no nursery with dead bodys, and teresa was with them the ENTIRE time.
tl;dr: book ≠movie