Perhaps the reason why this movie is getting such a bad rap is mainly a fault of its well-meaning, but still incoherent style and narrative structure. I have not read any articles on this movie or interviews with the director to know what his overt intention was, but in the end I think the movie falls short of its mark due to Kim's perennial fixation on obsession, whether it was his intention to delve into this subject matter or not. On most levels, obsession is a largely private affair, and any exegesis of obsession enmeshed within the loaded geopolitical situation that is now Korea would require a broader vision and canvas matched with a technical command of story telling than any that Kim has been able to provide here or elsewhere. However, one thing that I must praise Kim for is the reality with which he portrays military life in South Korea. It is, in my view, the grittiest, down-to-other depiction on the silver-screen of life as a grunt doing mandatory military service in Korea. I should know, since I've done my two years' service, as no doubt Kim also has. The situation might be unreal (a loose-cannon grunt suddenly acquiring the killing skills of Jason Bourne) but the military's reaction to it certainly wasn't. The ineptitude of the commanders to stop the problem, the fear of the soldiers and the conflict it breeds within, and, most important of all, the corporal punishment that gets amplified as it spreads down the chain of command.
So here's my recommendation: if you want a well thought out movie which pits issues of personal obsession against major geopolitical themes of our day, this movie is not for you. If, however, you want to see a curiosity piece about how troglodytic an existence military conscripts lead in South Korea, then you've come to the right place.