I'm rating this book for the effect it had on me when I read it as a child, not its literary quality. This book blew my mind as an elementary school student, mainly the shooting knids. Like most people, I had never considered that you could use fantasy to go to _space_. I wrote fan fiction about knids before I knew what fan fiction was. They also became the monsters under my bed, which is why I classify this as "horror" in my mind. 
 I argue that this book could be considered sci-fi, mainly because it got me thinking about stuff from space burning up in the atmosphere, but bad sci-fi because it made me think of the atmosphere more like a force field, so my fan fiction involved volcanos blowing holes in the "atmosphere", which allowed the knids to get through. Just the kind of stories primary school children should be writing. Thank you, Mr. Dahl.