As a review of the whole Southern Reach trilogy - 
 Authority and Acceptance were both solid books and provided an interesting broader view into Area X and its origins, as well as the Southern Reach itself. However, Annihilation was the stand-out favorite of the whole trilogy, to the point where I almost wish that VanderMeer had just stopped at Annihilation. Annihilation is so self-contained, weird, and gripping - sure, it leaves you with TONS of questions about Area X, but I think it would have been OK for none of those questions to be answered. As soon as I finished Annihilation, I wanted to delve back into Area X and learn more, but I don't think that the narrative structure of Authority or Acceptance was as effective as it might have been - I would have preferred to see more expedition journals from past and future expeditions. Acceptance was reasonably close to this, and I definitely enjoyed it more than Authority. 
 As another note on Acceptance itself - I really liked the narrative structure of 4 viewpoints in 3 timelines. It was very effective, allowing the reader to come to their own conclusions, which is ideal in an open-ended world such as this, full of unreliable narrators. I also, shockingly, enjoyed the 2nd person narrative of the Director - usually, I'm basically allergic to 2nd person (who isn't), but the POV's effect of removing agency from the protagonist and placing it in the hands of the narrator was actually very appropriate here. 
 So: Series: 4 stars 
 Annihilation: 5 stars, extremely deserving. Unexplained phenomena with an unreliable narrator? yes please! 
 Authority: 3.5 stars, drags in the middle and I found it hard to keep track of the characters. It's worth making your way through it to get to Acceptance, though. 
 Acceptance: 4 stars, not nearly as good as Annihilation but narratively engaging and cleverly constructed. Solidly enjoyable.