Mud has its flaws, including that it: (i) is about a half-hour too long; (ii) drags in parts; and (iii) steals many scenes and the gist of scenes from other movies albeit very good movies, such as El Camino, True Grit, and Stand by Me. But the spot-on casting and superb acting alone make the time spent with this movie worthwhile, and it is destined for an Oscar for best makeup or best special effects for Matthew McConaughey's teeth. And missing this movie would mean you miss the movie whose promotional premiere led to the kerfuffle Reese Witherspoon had with the law.
IMDb Link: http://www.imdb.com/title/tt1935179/?ref_=fn_al_tt_1
PS: If you are disappointed with the movie, this capture of profound disappointment should ease your pain: http://www.youtube.com/watch?v=MvbQ4wJak_c