Steven Den Beste has an article summing up his opinions on the films of Hayao Miyazaki. It's a good read. I'm a giant fan of Miyazaki's work myself, and SDB's post is interesting, even though I don't agree with him in all the particulars. In particular, I don't find Miyazaki's films terribly "preachy" at all -- but maybe I'm more simpatico with the general messages involved, so I tend to not find them heavy-handed in the first place. (Not that I'm immune to movie messages I agree with; as much as I love the Director's Cut of The Abyss, for example, that film drives its message home with all the subtlety of an Adam Sandler comedy.)
A couple of random points, only partially in response to SDB's article:
1. I love Castle in the Sky, but I have to grant SDB's point that the characters aren't the deepest that Miyazaki has created. Maybe with some stories, I'm more interested in the tale than I am in the characters? I'm not really sure here, but I know that I've greatly enjoyed, and counted more than a few among my absolute favorites, films whose characters aren't terribly interesting in themselves.
2. The Daughter just watched half of Totoro just this evening (turning it off at homework time). There just isn't a single misstep in this entire film. I find it immensely satisfying, and it doesn't leave me empty at all. I actually like the fact that this film gives just a tiny slice of one family's life, and doesn't even go more deeply than it needs to. We aren't forced to dwell on the mother's illness, and there's none of that "They could see Totoro while they were young and believed in magic, but as they aged they forgot" stuff that often turns up in magical stories about young children.
3. SDB doesn't mention another constant of Miyazaki's films: the music of composer Joe Hisaishi. I actually came to Miyazaki via the music of Hisaishi; I read a glowing review of the Princess Mononoke score and gave it a listen without seeing the film (longtime readers will know that I do not consider seeing the film to be prerequisite to enjoying a filmscore); the score became one of my all-time favorites more than a year before I had a chance to actually watch the film. The plucked strings and woodblocks of the kodamas sequence is an extraordinary passage of music.
Hisaishi has a very chameleonlike quality as a composer. He loves to use Eastern motifs in a Western musical idiom; these kinds of motifs abound in Totoro, Mononoke, and Spirited Away. For Kiki's Delivery Service, Hisaishi adopts an almost stereotypical French sound, with accordions and a lilting waltz for a main theme. His Castle in the Sky score is properly big and epic. (I have neither seen Howl's Moving Castle nor heard its score yet.)
4. To SDB's list of common Miyazaki themes, I'd add magical realism. All of Miyazaki's films involve fantastic elements to one degree or another (I did read one article once that argued fairly articulately that Castle in the Sky is even science fiction and not fantasy, but I'd still stick with the latter), but the treatment of magic is always very matter-of-fact. Miyazaki never stops the action for any kind of explanation of his magical events, and with the exception of Chihiro, no one is ever much surprised when magical things happen.
5. One of the things I most love about Miyazaki is the way he tosses tiny details into his films that are never remarked upon, never explained, and never figure into the main story at all. These little details are just there. Sometimes they greatly add to the depth of Miyazaki's universe, where other times they just add a small amount of "spice". Examples include Pazu's birds in Castle in the Sky and the dust-bunnies in Totoro. In this way, Miyazaki reminds me of George Lucas; the Star Wars films are chock full of small details that often mean less than fans seem to think they should. (Since Lucas is a known lover of Japanese cinema, perhaps someone can tell me if this is a facet of Japanese filmmaking in general, as opposed to being a unique quirk of Miyazaki's.)
6. Clouds. Seriously: I want to live in a world where the cities look like Lucas's Coruscant but boast Miyazaki's cloudscapes.