I'm a big anime fan, but anime movies tend to disappoint me. Princess Mononoke, however, not only doesn't disappoint, but sits at the apex of anime films. A boy named Ashitaka becomes infected with an incurable disease, and he journeys to its source to learn what he can before dying. He finds a world where nature is making its last stand against technology, and he is thrown into the middle of the struggle. Yes, you can see a pro-environmental message in this film if you really want to, but it's really more about coexistence.
But what really sets this movie apart is the animation. Now, Miyazaki would later dazzle the world with the even more creatively animated Spirited Away, but I've always felt that film revolved around its creative animation so much that the story suffered. Miyazaki has a knack for creating an interesting and vibrant world, and Princess Mononoke seems to balance that talent with an engaging and epic storyline. This world includes giant boars, wolves, and an elusive deer that might just represent nature itself. And as the forces on each side collide, Miyazaki takes the story in surprising directions, and ends the tale in a bittersweet, yet joyful way.
Of course, whenever the man vs. nature topic comes up in film, most of the time man is portrayed as evil. But here things are not so black and white. Both man and nature have their own understandable claim to the world they inhabit. This makes the characters far more complex than simple good guys and bad guys, and these characters stand out as a result.
Lastly, like with all anime, I would recommend the subbed version of this movie over the dub. Despite the long list of stars in the dub, hearing the Japanese language with a Japanese movie always feels more natural.