This movie is pretty good,it has a strong story and a strong cast,apart from Colin Farrell.
I can’t remember the exact date I started to dislike Mr Farrell but when ever I see his movies I find myself turned off,Total Recall,Alexander,Horrible bosses, London Boulevard,Miami vice are all movies that make me feel uncomfortably numb,he has very low range and really struggles playing the straight lead in this movie.
Sam Rockwell is an outstanding actor,he plays a psychopath and I enjoy his wild off the cuff performance,he delivers lines very naturally.
Christopher Walken is solid as usual but he is wasted in my opinion,there is one scene were Christopher Walken confront’s Woody Harrelson, it only last’s for sixty seconds but a cold chill went down my neck just seeing those cold eyes and ice cool vocal delivery for which Walken is famous for.
Not a bad idea for a movie but I think the casting of Farrell ruined what could have been a great movie.
6/10
KO
Movie Dr 
I liked it a lot more than you did but glad you singled out the great Christopher Walken.
Im not a Farrell fan be he wasnt bad and if he was everybody else was great to still deliver a great movie.
Last time I saw Farrell in a good movie I was watching Phone booth,that was over a decade ago,as he played the lead role it was hard to ignore his dense performance which in my eyes ruined this film,thanks for sharing your opinion.