So few books affect me with such a wide range of feeling, especially in so few pages, as this one. Fear. Wonder. Suspicion. Hope. Disgust. Surprise. Anger. And on and on, it certainly runs a gamut. The concept of "The Plan" with it's guiding master computer that controls everyone and everything, the elitist hierarchy, the punishment for "unplanned thought", all can be pointed to as troubling parallels for the extreme forms our political and social thought are taking. In a world with so many people and finite resource there is no room for individual growth, and everyone is forced to conform to "The Plan". Not doing so relegates you to the social status of a "Risk" and being forced to wear an explosive collar that can be detonated at anytime for unplanned action. The slow transition of learning just how unfair this society is from the point of view of the protagonist, his torture, and then his subsequent desire for freedom and answers to his questions will leave you with great empathy for him and other "Risks" in similar situations.
Once things move off of the Earth I found myself wanting to believe in the reefs of space and the spacelings with their mode travel. I want to go there!
The book does have a few problems and a few plot holes, but given the pacing of the overall story it is easy to disregard them... even though I think the experience could have been improved by resolving a few of them. Still, this one is definitely going on my list of favorite books.