I finally finished reading Raph Koster's A Theory Of Fun and although I disagree with almost everything he says, I still can't say it is a bad book.
All the way through his book he is hungup on the definition of Fun, and he can't seem to get past the notion that games are learning tools. Personally I see games as an entertainment medium, but he seems to believe they are a learning tool.
A lot of his ideas about how games are evolving by soup pot development and just building features ontop of what has come before is very conservative. You can see his viewpoint in action with his last two games that he worked on which where Star Wars Galaxies and Everquest2. Neither of which where trying to be creative, or something new.