A wild departure from Scalzi's pair of Heinlein-esque military SF novels (Old Man's War and The Ghost Brigades).
The novel opens at the trade negotiations between Earth and the Nidu, where Dirk Moeller creates a major interplanetary diplomatic incident by killing his Nidu counterpart. (Didn't mean to kill him, really; just wanted to make him really angry, but hey, these things happen...) What follows is a fast-paced comic romp, equal parts Douglas Adams and Eric Frank Russell.
A host of governmental offices are involved as Earth, desperate to save face and get back in the good graces of the Nidu, begins searching for a rare sheep -- the Android's Dream -- that is needed for the upcoming ceremony at which a new Nidu ruler will be crowned. The sheep is found in a most unexpected place, and becomes the object of a massive sheep-hunt and power struggle among rival Nidu factions, and human government officials with their own reasons to want the sheep to be found (or not found, as the case may be).
The story is a clever one, and there are sequences I liked very much; a chase scene involving special sneakers is lively and funny, and the climactic Nidu ceremony is sharply thought out. I'm afraid, though, that Scalzi's sense of humor and mine just don't synch up very well. I grew tired of his interchangeable bureaucrats (and yes, I realize that their blandness and interchangability is part of the joke), and thought he strained awfully hard for the throwaway digressions at which Adams excelled.
Scalzi's a talented writer, and if you enjoyed his earlier novels, by all means give this one a shot; humor's a subjective thing, and it's entirely possible that you'll find this to be the rollicking comedy it's meant to be. Just didn't work for me.