Stunning installment in an already excellent series. The writers understand two writing rules very well: One, 'intricate personalities do not make for engaging characters - their decisions do'. And this story was entirely driven by a set of characters making understandable, human choices faced with asymmetrical information, warped perceptions, and a hostile environment. The "villains", too, did what they did in the same framework as the more sympathetic characters and were thus entirely believable. Two, 'never let a coincidence be a good thing for your cast - only a bad thing'. The way the characters' choices and increasingly dangerous set environment cascaded together into an unpredictable, breathtaking and fast-paced plot was masterful. I couldn't put it down. 

There is one weakness persisting from the previous books that is keeping this from a perfect score. The plot deals with the profoundly unnerving and eldritch experience of alien life and touching down on an unknown planet. While there was some improvement over the previous book, the feeling of otherworldliness and strangeness just doesn't quite manifest.  I believe this is due to the writers' focus on dialogue and blockbuster-action. The plus side of this is that the writers got much better at crafting truly snappy and funny dialogue that feels less hollywood-y than in the first few books.