And I'd advise anyone that goes to see it to NOT read the book before seeing the movie. It was dizzying to have the movie plot going on while I had the book plot in my head. They're quite different. Many of the characterizations are very much the same, a few, in the movie are far more Japanese; but Miyazaki seems, I think, to have gotten the core of the people in the book and thrown out a lot of the stuff that wouldn't have made as good a movie. But it was stuff that had made the book very good indeed.
The book was definitely too complex and had far more character depth to be directly translated to a movie. But it was great stuff as a book. The movie did catch some of the best stuff, though, about the central characters. Missed entirely on a couple of the peripheral charaters, but were in-line with how they should have been.
It was quite the mental fight in my head over the two plots and, indeed, whole universe concepts.
I loved the movie and I loved the book, both for some of the same reasons and for some very, very different reasons.
The movie had that great character development, gorgeous detail work, beautiful contraptions, strong girls, and old character cameos that I've always loved in Mikazaki's work. That whole feeling of regular people who do regular things, most of the time, and then suddenly flower into something extraordinary. That's all there as wonderful as ever.
So I'll just say, don't read the book until AFTER the movie. It'll do a bunch more detail work about the characters for you, just be prepared for a very, very different central plot.