This note does not contain major spoilers for the book.

I've been looking forward to this, and finally got the book. Cosmonaut Keep was really interesting, and the universe was unusually interesting.

The first human starship flight is a success. (This is not a significant spoiler, you learn it right away.) The world they get to has a fascinating blend of completely weird cultures, and the political infighting is fully up to the MacLeod standard, which is the gold standard for this topic. The big political forces, including the Cosmonauts and the trading ship families, are all in play.

I found this one a lot of fun to read. It wouldn't be good for people unused to SF; it counts on too much picking up strange details on-the-fly, and in some cases living with the strangeness for a while until enough detail is picked up to make sense of it. It's all very well done, too. Definitely required reading for those who want to know what's interesting in modern SF.