Almost every movie lives and dies in its genre; animation doubly so. Princess Mononoke is one of the very few animated films (out of perhaps five or six total in history) that stands first and foremost as a film, not an animated product. What we see is too fantastic to be "real," but the story is told with such conviction and strength that we accept it entirely on its own terms.
Such is the hallmark of any excellent movie, actually. Mononoke stands out for being both an animated production and the product of Hayao Miyazaki's animation house, Studio Ghibli. Miyazaki is probably responsible, more than almost anyone else in the history of Japanese animation, for productions that not only stood out in their field but ennobled the rest of it by mere association. My Neighbor Totoro, Nausicaa of the Valley of the Wind, Whisper of the Heart, Grave of the Fireflies, Kiki's Delivery Service and Porco Rosso are all both beautiful and thoughtful.
Mononoke stands out from the rest of Miyazaki's works by dint of being possibly the best of them all -- as well as the most matter-of-factly violent. The underpinning of the story is man's often brutal relationship to nature, "red in tooth and claw." There is little sentimentality about the fact that people die, often pointlessly. There is also something else that many films of any variety do not have -- a level of moral ambiguity about its characters that forces us to see what happens from multiple angles. There is no stereotyped villain in a black cloak; the most "evil" character we see is in fact extremely sensible and pragmatic in her motives, and the "good" characters are sometimes deeply misguided. They are, in short, human.
