I can think of no better author for this book than Frederik Schodt. He was one of the first American "otaku," a leader in early Japanese-to-English manga translations and imports, translator of works such as Barefoot Gen, Astro Boy, The Rose of Versailles and Phoenix, writer of the groundbreaking Manga! Manga!, and personal friend of Osamu Tezuka. He's done so much to establish Japan as a major cultural producer internationally that he was given the Order of the Rising Sun by the Japanese government in 2009, AND the Tezuka Cultural Prize in 2000. He doesn't just know his material - he's been intimately involved with it for decades.
Astro Boy Essays was an easy and engaging read, given my high level of interest in the material, and I found it to be built in such a way that it was both plugged into the moment in which it was written and of lasting value. Manga! Manga! is written in this way, as well: though very much a product of the late '80s, its value as a primer history of manga up to that point and as a snapshot of manga culture at the time remains high.
Schodt's writing style is journalistic more than it is scholarly, and you won't find any complex sociological theories here - but for what it is, his work is damned near perfect, and his influence has been enormous.
As for Tezuka-Sensei himself, what needs be said? Certainly a worthy subject.