The movie uniquely dealt with the mechanism of coping with traumatic experiences. True, it was a war pic. Yes, it had an additional "look what we're doing to our kids" anti-war message (which was driven home in the scene where he's finally leaving his son's barracks and this young, pimply faced kid starts settling in), and yes, it was a murder mystery, but the method in which Haggis portrays the different behaviors the characters exhibit while trying to deal with extremely stressful and traumatic experiences was the main point of the movie.
Haggis drove the point home with careful camera techniques and crafting true-to-life characters. I like the way he kept the camera back at the end of the hallway when Mrs. Deerfield cried into her husband's arms after viewing the mutilated body of her son. He employed a similar method when she broke down and started crying on the phone (Mr. Deerfield: "I'm not gonna sit on the phone and listen to you cry." Mrs. Deerfield: "Then don't") Deakins has the camera up on the stairs looking directly down on her while she sits hunched over on the floor. It's not that Haggis is "hiding" these moments from the audience I believe that it is more of a commentary on our disconnection from our own emotions during these moments.
Additionally, Haggis has the actors restrain themselves during the height of when one expects them to indicate the most suffering and when the camera is close enough to expose it, i.e. Mr. Deerfield seeing his mutilated son for the first time, also towards the end when he realizes that his own rigid personality alienated his son from himself and Cpl. Penning's almost robotic, non-remorseful confession of murdering Spc. Deerfield which was a phenomenal performance are two good examples. You could see the mountain of emotion being suppressed behind his cold exterior. His confession was so level that it was hard for me to accept the fact that he had stabbed Pfc. Deerfield over 42 times, dismembered his body, then set fire to it. But this is exactly the point Haggis was trying to make this disconnection from reality; death as a video game with no consequences ("React or die. React or die.") By the way, I think Tommy Lee Jones did an amazing job as well. And that's an understatement.
Further exposés on the aspects of coping include the side story of the soldier who first held down his Doberman in the tub until it drowned and subsequently repeated that action with his wife instead. Spc. Bonner hanging himself for his involvement in the murder of Deerfield. Pvt. Ortiez's full denial of the fact that their squad ran over an Iraqi child ("That wasn't no kid. That was a dog. As far as I'm concerned, that was a dog. I don't know what that picture is."). More importantly, Spc. Deerfield's own methods of coping served to act as the catalyst for the plot. The one moment he had (and the only moment in the movie where tears are actually shown falling) where he tried to reach out to his father ("Dad, something happened. Can you get me out of here?"), he got snubbed. So his ability to cope manifested itself into destructive behavior: doing drugs, bad-mouthing the stripper, torturing the "Haji" militant, picking fights with his comrades ultimately leading to his demise. All of these characters had their demons to deal with. The point of the movie was how to deal with those monsters. The title, itself, acting as a metaphor to that exact question. The Valley of Elah where David took his stand against Goliath was where all the characters of this movie stood in the shadows of their own Goliaths. Some fought (Mrs. Deerfield, Det. Sanders), some stuck their heads in the sand (Ortiez, Mr. Deerfield), and some ran away (Penning, Bonner). Much like the tagline states: sometimes finding the truth is easier than facing it.
I also thought the movie was unique in the angle it took on war: its psychological impact. Excluding such crappy movies like, "Iron Eagles" and "Flight of the Intruder", good war movies have more than an "accomplishing-an-objective" plot type in mind. "Saving Private Ryan", although based entirely around an objective, used the multitude of horrors the characters encountered to highlight their methods of dealing with it. I'd say this movie was more along the lines of "Deer Hunter" or "Jarhead" where what you see in war plays second fiddle to how you deal with what you see in war.
The only objection I had to the movie (a very moderate one) was originated by my girlfriend, who served in Iraq I hadn't thought about it until she brought it up. True, the movie is a very small "slice of life" take on our involvement in Iraq (granted, PTSD is a MAJOR aspect of this war but there are many other facets as well), so it's not entirely unjustified to have ALL the soldiers of this movie be so "f***ed up" from their wartime experiences. However, it would have been nice to see at least one soldier try to cope with his demons in a more constructive way be it counseling or in some other non-destructive method. When I visited my girlfriend in Germany, during her leave, I came across pamphlets, brochures, and television commercials (on the Armed Services Network) that encouraged infantry men and women to seek counseling in helping deal with PTSD, acclimating to life in the states again, returning to their families, and so forth. Nevertheless, personally, I don't feel that this is too critical of a point to make Haggis is trying to illustrate a specific notion of the effects of war and shouldn't have to cater to any of the "exceptions to the rule."