Mysteries/thrillers are probably my favorite genre to read (and heck, my favorite movie genre too). I like puzzles and trying to solve the mystery. So, if for no other reason, this was a fun puzzle for me to solve (and I kind of did but then doubted myself and changed my theory, always go with your gut feeling!). And if you like fast paced mystery thrillers then definitely read this (although at this point I think most everyone has already read this, I'm late to the game). 
 I can definitely understand the comparisons to Gone Girl, this is a story about deeply flawed people that wind up in some very bad situations. Rachel, the main character, is an alcoholic, which makes her an unreliable narrator. Sort of. She is never clear on her memories (thanks to alcohol induced black outs) but she never flat out lies to the reader either so she's not completely untrustworthy. I mean, none of the characters are particularly likable but somehow that works well for the story. Sort of like a car crash, it's terrible but you can't look away. And Rachel has so many moments where I wanted to shake her and scream "NOOOOOO DON'T DO THATTTT". 
 Hawkins definitely wrote a really great and gripping story. She definitely excelled at creating well rounded characters and is an excellent thriller writer. The best part about this book is that it feels like a look into someone else's messy life- it's nice and enjoyable to peek in but then be able to walk away, thinking "yikes, at least my life isn't that bad..."