I went to see Annihilation last weekend and I really enjoyed it. The movie is visually stunning and the pacing of the movie is near perfect. I thought it struck a perfect balance of sci-fi intrigue, thriller level suspense, and reasonable action scenes. The characters were well cast for their roles in the mission and their motivations and resulting character development after entering the shimmer are fascinating to watch.
There is a bit of a disparity on Rotten Tomatoes between audience and critics' scores. I think this boils down to the ending, which I won't spoil, but make a general comment about the sci-fi genre. Often questions are left after the ending of the movie. I don't think the average movie goer likes the lack of conclusion or ambiguity. I think that's the point of harder sci-fi movies like Interstellar, Blade Runner 2049, and it holds true with Annihilation.
Highly recommend going to see this in theaters, but be prepared to do some brain thinking so it doesn't leave you disappointed in the end. Let me know what you guys thought or if you are planning to see it.