I wasn't sure what I was getting into when I opened this book. I think that's exactly what Gaiman intended, so I won't give away too much of the story, except to tell you it's a fast-paced Doctor-Who-style* story for kids, with dinosaurs, aliens, pirates, and a volcano. It's fun and funny, and it can be read out loud in half an hour. The frequent illustrations are a nice touch too, and are nicely expressive. Get this book from the library and read it to your kids or your self.
*(The Doctor Who connections may not be obvious to non-fans, by the way, but to those with ears to hear they are unmistakeable.)