I was compelled to finish watching the film only after I was in the second half; till that point things seemed half-baked, witless, and barely interesting.
When I first saw the poster, I saw Natalie Portman, with gun and a crew, against a misty forest backdrop. I immediately thought of survival, war, and Predator-esque alien encounter. Needless to add, I was sold.
But, turns out, nothing much was like it. And honestly, it didn't matter.
Visuals are good, and certain concepts (and scares) one-of-a-kind. My inquisitiveness throughout, much like some characters in the film, was intact, till the end.
What I didn't like was that there were liberties being taken, that there were actions being rationalized—for example, Portman's character suddenly knows how to use a gun, and that too adroitly; only later we are told she had had a military background.
Even tactically, things seemed a bit off: If I were to empathize and become one with the crew, I as a lay person, would have thought of doing a lot of things differently for my survival and the mission. And these people, who are scientists and with military intelligence, didn't know even the basics.
Annihilation makes for an interesting watch only if you keep your thinking aside for a bit and indulge in the novelties the film has on offer. In any case, the film won't bore you.