I'd give 4.5 if Amazon would let me! A great, fun story, full of suspense, tension, the wonders of alien contact -- as well as the plentiful opportunities for faux pas! The relationship between the different species, but especially Brai, was fascinating. Jane Hollaway is a great protagonist, struggling to lead her crew while also not offending aliens with entirely different sensibilities.
The story picks up pretty much where Fluency left off, and there's not much filling in of backstory. You pick it up as you go along. Nevertheless, I expected a bit more reaction, even a sense of wonder when they landed on another planet and met a new species. This was the case in Fluency, so perhaps it was no longer so new to them.
I liked how the relationship between Jane and Alan developed. Very realistic with its ups and downs. The various dynamics at work among the crew hints at the troubles that will brew for the crew in the next book. And they've definitely got their work cut out for them. That ending left me wishing the next book was out *now*!