It is a fantastic movie. I won't go into detail about the story, but I did see many elements that Miyazaki used/re-used in his later movies. Once again, it becomes apparent that Miyazaki is an airplane geek (as we also saw in Laputa), and that he feels strongly about conservationism and Gaia theory (which I got acquainted with via the DaisyWorld model in Maxim's SimEarth) -- a theme that also prominently figures in Princess Mononoke. There is a theme of implicit trusting nature, and the endings of both Nausicaä and Mononoke both figure that theme quite strongly.
I give this movie my unreserved recommendations.
I wish we could hold an Ohmu in our back yard -- they're cute!