This volume is generally one of the less popular among Bujold fans, probably due to the absence of Bujold's most celebrated character, Miles Vorkosigan. But it's a solid story with pleasures of its own.
Ethan comes from Athos, a planet founded by misogynists who took their loathing of women so seriously that they founded a planet populated only by men. Uterine replicator have been used for reproduction, but now they are failing and there is a need to import fresh genetic material, so Ethan is sent to Klein Station to pick up new materials.
On Klein Station, Ethan encounters betrayal and conspiracies from galactic powers that isolated Athosians have little understanding of. His only ally is Elli Quinn of the Free Dendarii mercenaries.
Wild adventures ensue, with the usual amount of double-crosses, mysteries, and sudden plot twists, all of which are handled well and are a sufficient reason to read the book. But the greatest pleasure in this story for me is the Bulold's world-building. She has really thought about Athos and about Klein Station, and she creates them as plausible places, showing what they are like. And, as another reviewer has properly pointed out, she shows the uniqueness of these societies not with long chunks of exposition that break up the story, or characters who deliver implausible lectures on the differences between their societies and 20th Century Earth, but by allowing you to see events from the perspective of people from those societies.
This isn't Bujold's best. But it's an illustration that Bujold, even a bit off form, is still better than most and a very rewarding writer.
Because this book doesn't include Miles Vorkosigan and his complicated personal issues, it will be an easier read than most Bujold books for somebody unfamiliar with the series.