Good stuff, I waffled between giving it 3 or 4 stars...but ultimately, it's best read after The Last Colony, where it explains the huge deus-ex-machina. However, Scalzi really does handle emotions wonderfully....The scene at the end between Zoe and the alien Obin made me cry. 
 Laugh and cry, and wish I were just as smart...that's what Scalzi's books make me do.