Like all of Lumet's better movies, "The Hill" is well executed, poignant in its ethical and psychological messages, but marred by a Manichean over-simplification of morality.
Concentration---urr, "retraining", then---camp, for those of your own, is full of possibilities for a nuanced moral examination, of our values, and our code of propriety. Having a protagonist as despicable and readily hated as Sgt. Williams weakens---not strengthens---the film's message for an intelligent audience. Even the treatment of gruff Sgt. Major Bert Wilson, convincingly complex as he is, could have used more subtlety and balance: he shouldn't have been so easily manipulatable by Williams, should he? A bit more of an old soldier's contempt for a mere "civvy"---a physically weak and mentally unsound one at that--- would have made him look less like an easy sucker, and brought more credibility to the character.
The above being said, the film still did something refreshing for today's audience: not just the ready cliché in "Power corrupts", but more importantly, HOW power corrupts through "forms" and "precedents" and a Lear-like patriarchial persistence, and how insensitivity to human suffering that makes a person "effective" in certain working circumstances, can creep up his otherwise robust psychological frame, and fester into sadism.