Hmm. There were a couple of nagging problems with this book. First is the way the anthropomorphism was executed. While I have no problem with the authors turning the planet into a cartoony character with a secret to tell (a retro 1960s planetarium sort of thing), the character's imagined dialog with scientists twists the logic. The whole book is based on the idea that Pluto was 'hiding the secret' that it wasn't a planet from scientists for decades, when really this was more about the emergent nature of this field of inquiry. The worst of it is when the character seems to be leading the scientists, as if it had the definition all along, which objectifies this committee decision as discovery of 'Truth' in ways that aren't right for this situation.
Second, Weitekamp and DeVorkin skirt the issue of significance. When and why does it matter whether something is called a planet or not? The third criterion for defining a planet (it must be alone in its orbit) is fraught with billions of imminently discoverable exceptions outside our solar system (very earth-centric). What will happen when astronomers discover an orbit around another star, one with TWO round objects in it, each directly opposite the other waltzing around their sun?
The upshot is that celebrating this committee decision on Pluto as if it were a new miraculous discovery about the nature of Pluto is misleading. Despite all this, the basic facts of Pluto's discovery and characteristics are present in the book. Collaboration with the National Air and Space Museum lends credibility, and the bibliography provides key source material--I'm intrigued to give Mike Brown's book a look. Along with other back matter, the book can lead to a deeper inquiry.