Here, Prospero refers to Caliban as his "slave," who never speaks nicely. Miranda calls him a villain she hates to look at.
From these words, both Miranda and Caliban clearly dislike Caliban. However, they also admit they need him, because he performs important tasks like lighting the fire, fetching the wood, and basically doing everything they don't want to do.
When Caliban does appear, they call him a "poisonous" and the son of the devil and his "wicked" mother.
As a result, the reader is predisposed to dislike Caliban and find him monstrous. However, a little more reflection shows that Caliban is being very badly treated. No wonder, then, Caliban is always miserable and unkind.
