I bought this book after seeing the movie Annihilation, which really was bizarre ( I think I liked it, but I couldn't really understand the subtleties that are usually present in a book form).
So, first of all the movie and the book have little to do with each other...the book is much more detailed, much longer, and much more bizarre (yeah, who knew it could be?). The book was more grounded in some ways (not all the team were carry automatic weapons for instance - which was just silly in the first place if they are not military). The book was less grounded in other ways... A giant staircase in the ground? - why exactly?
You come out understanding the bigger picture from the book - IF you can survive reading some of the very detailed and pointless writing. So yeah, by reading the book some of the movie questions were answered, but I ended up with a LOT more unanswered questions than I started with.
Overall, I doubt I will ever suffer through reading this book again. It has a really good basic plot that is twisted and tortured into near obscurity. It is chalk-full of ridiculous events. It has many wonderfully alien events and plot points as well. I left the book unsatisfied, a bit depressed, exhausted, and relieved it was over. Not my usual sort of book.