I have thought of this a long time ago that when you exactly execute a story from a book to a movie, it won't make sense at all. Perhaps you know why, not all senses can be applied to both. And mostly you get disappointed when it appears on the screen.
But not for THE MAZE RUNNER.
I have watched it first before I finished reading the book. Movie is really good, I was even screaming inside the movie theater for its outstanding cinematography. However, reading it was better. Why? You get to know more details that didn't appear in the movie and you'll understand why it can't be there (You do not need to be a film or a Communication Arts major to understand, just using your common sense will do). Just like the ending of the movie, they were rescued by men and brought to the helicopter. In the book, they were rescued but brought to the bus. The people watching the movie needed more visual excitement than just flat watching a boring bus going to its destination. Showing the entire maze from above was better, yes? There were so many alterations from the original story, but you can still appreciate both. And I'd like to congratulate the screenwriter for not disappointing me. He actually did well in his part.
Bottomline, just because you have watched the movie based from a book doesn't mean you'll lose your excitement when you read it. If you think you know the entire story by just watching, I promise you, you haven't. I have proven that to myself several times by watching and reading both counterparts of different stories. Cite, Twilight Saga! I bet majority of you got hooked in the movie even if you know the books were way better (and just so you know, the screenwriter of Twilight really sucked but many still enjoyed watching. It could have been better, right?). So as The Mortal Instrument, Divergent, The Fault in Our Stars, The Hunger Games trilogy, Nicholas Sparks stories and many other more.
P.S. If you have read it first before watching the movie, try to ask yourself "Will it be flabbergasting if ________ in the movie?"
P.P.S. Screenwriters also have a big responsibility to keep you interested watching the movie.
P.P.P.S. I suggest you do the same. It's a good exercise for the mind!