Children’s scifi is a meager genre, and the Norby books stand out as being a little more fun than most. They’re not comedies, certainly, but are less tedious than many scifi books I’ve come across. My biggest complaint is how for the first chapter of every book (asside from the first) is always spent summarising the backstory in a very clumsy and stupid-sounding dialogue. Once you’re past that, it picks up.