Eeeek I loved this! Super similar to The Girl on the Train, but still had very little predictability.
Even though the "thriller" bit of it was a bit slow-moving, I liked the story leading up unto that point. Gillian Flynn's writing on Amy & Nick's backstory was really captivating. I especially loved Amy's commentary on getting into a relationship and trying to be the "cool girl", and then being labeled psycho when you no longer want to be said 'cool girl' in your relationship. There were a lot of these sorts of themes that make you really not know who to root for!
I found it so interesting the extra level of having so much manipulation and ill-will in a relationship that you are seriously on both characters' sides throughout the whole story. Even by the end... Amy is obviously very crazy, but has also been hurt by not being 'seen' by Nick. We know that Nick is not the best husband to Amy, but being framed for murder also makes it fair that he doesn't like her anymore! I even got conflicted over feelings about Desi... is he actually obsessive, or is that just how Amy portrays him? And did he really lock her up, or was that an Amy-ploy?
I loved every part. Amy's bout of hiding in the Ozarks, Nick's putting on a good face on TV, and even the neighbor, Naomi's involvement. And the whole true-crime feel of learning how Amy set it all up. I watched the movie after which was also really well done! But the book was better ;-)