Solid thriller with a satisfying ending. Gripping enough that I tore through it in a matter of days. I appreciated that I was engaged enough that I didn't guess the mystery until it the story's third act, and that when the truth was revealed it was satisfying for both plot and character reasons. 
 (view spoiler)[ I would have liked a little more resolution with the secondary characters in the denouement, especially Riley, the woman detective. I expected her to come to an understanding with Rachel, or to see and understand, but we weren't given that. That would have been too victorious for her, I suppose. Similarly Rachel's relationships with Anna and Scott were never resolved. Another gripe. I don't understand why she and Anna had to create a story that Tom came at her with a corkscrew. Tom's a big guy, and given he attacked her with a bottle I think she could be forgiven for responding with a weapon. At that point I think the truth would have been enough to claim self defense, as it certainly was. But then again I'm not sure if Tom was posthumously convicted of Megan's murder. Presumably that was part of what Anna and Rachel told police, otherwise Scott would still be under suspicion for Megan's murder. But they don't tell us if the police ever recover the damning cell phone, or check Tom's DNA against Megan's unborn child. Sure, you want to wrap things up quickly at the end of a book like this, and it's part of the book's aesthetic to leave loose ends. But I would have appreciated a little more detail on the technicalities of the resolution. (hide spoiler)] 
 Overall I very much enjoyed the read, and found the plot more satisfying than Gone Girl (which, full disclosure, I have only seen not read). Definitely check it out.