The author of the book is one of the producers - they did it justice. This one is worth seeing, make sure you watch the video when it comes out.
The movie had a reputation of being a "chick flick" but the Dunkirk scene and overall theme of trying to atone for a terrible and inexcusable action that can never be taken back really appealed to me.
I almost put down the book during the first 100 pages but then it really picked up after that. I highly recommend it and sticking through the first section which is all about setting the scene for the actions to come later.