This book is also about music out of it's place. Rock and roll passes through Discworld, and the results are great (great meaning comedically bad). Take a very detailed and complete fantasy world, add the rebellion of rock and roll, and it seems like it writes itself. But the great part about this, and all Terry Pratchett books, is that the joke only begins with the setup, the entire book just keeps getting funnier and funnier. (Compare this to The Onion, where the entire joke is in the headline, and the story is usually just fluff.)
Finally, like all Pratchett books, through all of the ridiculous situations and absurd logic, there is a decent amount of drama at the end.
If you already know and like Terry Pratchett, here's one of his best works on Death. If you don't know him yet, you could easily start with this book. This was the second Pratchett book I ever read, and I haven't stopped since.
