I'll admit that going into the theater to see this movie I knew little to nothing about it apart from seeing a snippet of the trailer. It struck me as very Cohen brothers-esque, a dark comedy that would challenge the viewer upon viewing, but I feel like that sells this movie drastically short. The story centers around a woman's quest for justice in the unsolved murder of her daughter, but again that would be a massive oversimplification.
If you have seen Martin McDonagh's other work In Bruges, then you may be somewhat familiar with his style of storytelling. The characters in his films reveal themselves to you in layers, at first seeming easy to pin down and form opinions of. He allows you to feel like you have a firm grip on the core being or personal motivations of someone in the film and then when you least expect it he turns all that you think you know on its head. Setting the film in rural Missouri at first seems innocuous, but you realize that it unconsciously informs your oversimplification in judging the characters. Frances McDormand (Mildred), Woody Harrelson (Sheriff Bill Willoughby) and Sam Rockwell (Officer Jason Dixon) were perfect choices as each has made a career playing the complicated, nuanced and tortured. Caleb Landry Jones (Red) steals several scenes in this film from his more illustrious co-stars and is certainly someone to look out for in the future.
In conclusion, this movie is worth seeing merely to challenge your own morality and sensibilities. Multiple times during this film, I found myself at odds with my self. One minute things would have gone so far into the darkness that it felt like there simply was no way back into the light; then I would be laughing. It forces you to come to the conclusion that perhaps there is no such thing as black and white, just various shades of grey.