I liked this second book in the series better than the first, Only You Can Save Mankind. The characters are quirky, interesting and most of them are dead. Pratchett's humor is always wonderful and usually insightful.
I liked this passage:
It occurred to Johnny again that the human mind, of which each of his friends was in possession of one almost standard sample, was like a compass. No matter how much you shook it up, no matter what happened to it, sooner or later it would end up pointing the same way.If you are trying to encourage a young reader I think this book would be great. And I would go with this one rather than the first, it really doesn't need to be read in order. The suggested reading level is ages 9-12, but I think it can be appreciated by much older readers, too.