Tommy Lee Jones
The movie falters the worst when it moves focus away from Jones' character study, opting to present the unraveling mystery through an unexciting police procedural. It falls prey to predictability far too often, especially if you've seen any number of the million cop shows on TV. Most annoying is the way Jones seems to be smarter than the entire police force working the case.
What keeps things from completely unraveling is the destruction of the film's characters, and the very compelling way Jones' son is slowly revealed to have basically been a total asshole. Most movies would've gone the other route, presenting him as an honorable, earnest soldier serving to make his country a better place, and then used his regrettable death as a catalyst for U.S.-bashing. Say what you will about Paul Haggis, but he's better than that, and it shows.
In the Valley of Elah: After Iraq (27:35): An interesting and informative look at the making of the film.
In the Valley of Elah: Coming Home (15:20): A continuation of the first featurette, this time focusing on the cast's/crew's views on the war.
Also included is an Additional Scene (7:46).