I found this movie extremely engaging, with an excellent story. Not having read the book, nor being a fan of Mel Gibson I rented on Prime just to see the performances. However, the movie far exceeded my expectations, and not just for the performances. To me it gets an A+ in story, acting, score and most of all, character development.
I could not understand how this movie was not in wide release in theaters and then found out the story behind the disagreements between the studio, the director and Mr. Gibson. If I'm not mistaken the director even used a pseudonym PB Shemran so he would not be attached to the project. However, I found this to be an excellent movie, engaging throughout.
Watch it without hesitation, I don't believe you will regret it.