This is the sequel to Bear's Forge of God though its quite feasible to read each as a standalone-they bear very little relation to each other!
Basically this is a space opera kind of story, where the descendants of the first book are set on a long voyage to-well I can't give the details without giving spoilers to the first book! At times it was tedious, longwinded and the characters I found really annoying. Imagine being stuck on a ship filled with teenagers! Think Lord of the Flies set in space!
But I plodded through the near-500 page tome and in the end I found I was glad I persisted-it had a satisfying conclusion. In the middle of the book Bear suddenly gets his Hard SF head on, dealing with time/space dilation and quantum mechanics, BUT its not intrusive or hard to read-it doesnt spoil the flow of the book if you were enjoying the voyage.
Not as immediately enjoyable as Forge but by no means bad!