This book brought up a lot of really interesting ideas about resources and the value of things if there was an infinite amount of resources. What would be valuable then? I liked the main character, Joshua, a lot. As for the spirit of the ancient Tibetan who had transfered into circuitry . . . well, I'm not sure what I thought. He was alternately irritating and likeable but made for an interesting foil against Joshua and, eventually, Sally. I thought Terry Pratchett did a great job exploring a lot of the issues that would arise if we were suddenly to find ourselves with an infinite number of earths to explore and exploit. My only complaint was the ending--the story just cut off. Obviously there needs to be a sequel but I wish that the end had felt more rounded off rather than snapped.