In many ways this is my favorite of the four robot books. The characters, especially, Giskard and Daneel, were more developed. I find the robot characters so much more interesting in this series: in particular the way they reason through the problems facing them, and even evolve. Though I did like DG and thought was also more compelling. Since this is a reread, it is cool to see how Asimov uses this to set the stage for both the galactic novels and the foundation series. One can see the tension between Asimov's individualism (his respect for and admiration of individuals) and his philosophic commitment to a kind of benevolent (as he sees it) collectivism. Through his characters he is seemingly trying to work out how to integrate these contrary views. In some ways, this is the most explicit of the four in this regard.