Frederik Schodt is always worth reading, and while "The Astro Boy Essays" is mistitled, because it's really not a collection of essays, it's a book on the Astro Boy phenomenon and Osamu Tezuka with different chapter. In fact, the most essay-like chapter, where he discusses the role of robots in manga and the world, is the weakest one. He really shines when he tells us about the history of Tezuka and his work; as an introducer of manga and manga history, he's hard to beat.
Tezuka, the "God of Manga", comes across as more complicated than the "creator of nice or melodramatic stories" that he has had a bit of an image as, and Schodt also tells us how this came to be; how the Astro Boy TV series sort of diluted the premise of the manga stories, turning it more into heroic action and good vs evil than the problematization of science and technology.
One thing I'm taking away from this book is how sad it was that Tezuka became a company executive, instead of spending all his time creating more manga and stories for the animation studio. Another is Tezuka's deep revulsion for war, based to a large extent on his (and Japan's) experience from WWII and the occupation. I've also become tempted to read the entire Astro Boy series which I've previously skipped because of it's children's comics look, but there's a pretty long line of things to read now.
Anyway, this is a very good introduction to the Astro Boy phenomenon -- and not just an introduction; it's an excellent, pretty in-depth book on the subject and warmly recommended.