Princess Mononoke is the third of Hayao Miyazaki's classic anime productions dubbed by Disney for the North American market. Adapted by Neil Gaiman, it shares the wild imagination and artistry of Miyazaki's Castle in the Sky and the depth and complexity of Spirited Away. It is also clearly not for children.
In a remote village in eastern Japan, a young man named Ashitaka confronts a rampaging demon which turns out to be a gigantic boar-god covered in disgusting, oily, wriggling worm-like growths. Ashitaka is able to defeat the insane god-turned-demon, but is touched by the growths and his arm grows black. An autopsy reveals a hunk of worked iron inside the boar; this object was what drove the boar-god insane.
His fellow villagers know that Ashitaka now carries the boar-god's curse and that he will soon go insane with hatred and die. To protect his village as much as to find a cure, Ashitaka heads west, to find the source of the boar-god's illness and do something about it. After a long journey, he discovers a settlement named Irontown, beset by rampaging Samurai.
The head of Irontown, Lady Eboshi, has built this mining colony and has provided labour and a good life for her workers, who include young women rescued from brothels, and lepers. Lady Eboshi's Irontown, however, is the source of the iron that drove the boar-god insane. Irontown was carved out of a forest, and the cost to the trees and the animal life have enfuriated the huge animal-gods that populate the stricken forest, and the two sides have become mortal enemies, sworn to each other's destruction. Facing Lady Eboshi is Princess Mononoke, a wild young girl raised by wolf-gods. As the two sides rush headlong into war, Ashitaka realizes that he must somehow make peace between them, lest the curse that afflicts him destroys everything and everyone.
Princess Mononoke retells a piece of Japanese folklore which, according to sources, is "set during the Muromachi Period (1333-1568)". There is incredible depth in this story, and Miyazaki rises to the occasion with visuals that are both wonderful and terrifying. The story is hard to follow, but it is impressive in its complexity and depth of character. There are few outright evil characters here (the Samurai squadrons come the closest). Lady Eboshi may be the cause of all of this conflict, but she earns the loyalty and respect of the people beneath her, and she can be reasoned with when necessary. On the other hand, the animal gods and princess Mononoke are entirely justified in their anger, but the depth of their anger prompts them to do some irrational, destructive, but ultimately all-too-understandable things. Even though the princess becomes something of Ashitaka's love interest, he does not side with her in the struggle. The real enemy is not one side or the other, but their combined hatred and stupidity. Ashitaka's struggle is to try and find a way to convince both sides to live in peace. To say that he has his work cut out for him is an understatement.
Princess Mononoke is not for children. It is far more violent than either Spirited Away or Castle in the Sky, and some of the visuals range from horrible to downright apocalyptic. Touches of humour are available but don't come as frequently. One character has a chance to utter the line: "Don't worry! It's just a bloated, brainless god of death, but it's almost sunrise! It will go away!", but the humour is lost in an impressive climax that drives home the futility of war and of humanity and nature in conflict.
Despite the movie's depth, I'd have to rate both Spirited Away and Castle in the Sky higher in terms of my personal enjoyment. While the characters are strong, the rapport isn't as effective. The movie also ends rather abruptly, pulling a happy ending out of its hat which, while not unreasonable, still seems a little out of sync from the several minutes of widespread destruction that precedes it.
Overall, I'd still recommend the film. The visuals will keep your attention and the storytelling is still compelling. The movie's dubbing is as effective as the previous two imports. All in all, you'll be in for a treat, though you will not be left with as strong of a sense of contentment as after watching Castle in the Sky.