The basic theme of the book - and this theme has been retained in the movie - is the strong oppressing the weak, the weak fighting back against this tyranny. It is in every story, though treated in a variety of ways. Slavery and freedom, bondage and liberty. You have these two poles right the way through the film, and the conflict between them is at the centre of the narrative..
What the Wachowskis and Tom Tykwer - the directors of the film - have done, very cleverly, is to cinematize the literary version of the story. The visuals are impressive, the makeup is dodgy in parts but spectacular in others, the directors seem more at home with the sci-fi stories but manage them all well.