What similarities does Pratchett's Discworld have with the real world?

What effect do the fantasy cliches have on the novel?

Pratchett often leaves things unexplained. Does this add or take away from novel?

In such a magical world why are so many surprised at the powers of Luggage?

In what ways does the fact the Discworld is a series of books affect the novel characterization?

What parodies of pop and fantasy culture can you see in the novel?

There are very few bad or evil characters in the novel. What meaning does this give the Discworld? How does the concept of evil change when the world is on the verge of destruction?