This was one of the first hard science fiction novels I read and I still feel the force behind the emotional climaxe ten years later.
Bear creates a totally believable world, which has been changed almost beyond recognition by nano-technology. It is a world where humans shapes can be customised to suit their wildest taste, and the human mind can be entered and traversed by a therapist in 'virtual' physical form.
But for all Bear's inventivness of character, the reader never feels any great sympathy for their trials and tribulations. This is saved for a computer.
The unforgetable moment in the book is when a enourmously complex and powerful computer, becomes self aware, in a part of space where an answer to a question takes over a year to return. It is a testement to Bear that he is able to make the subject for such a moving moment, emotive science, a computer's unconsolable isolation and lonleness in an unreachable void.
Truely great science fiction and while the rest of the novel is clearly flawedand suffers from Bear's trademark stagnation of pace and looseness of plot control, this moment alone makes the book a significant milestone in science fiction.