I guess the main thing I can say about "Dark Places" is that made me uncomfortable while reading it - but not in a bad way. 
 I was expecting something like "Gone Girl" but, even though it has the same kind of "mentally unbalanced in a dark way" characters (I really don't know how to put it in another way), the story is completely different. (view spoiler)[ And that's good, even though it made the end kind of unsatisfying in a way. I mean, all though the book I was thinking that Ben had everything against him, it was just bad luck after bad luck! The panties under the bed? The whatever in his locker? Come on! And in the end, what was it? Just a combination of unfortunate events. I didn't see the girlfriend thing coming, but as for the mother's decision, that was something I've thought from the beginning. 
 I did suffer from the characters problems, but most of the time I was thinking "What the hell is wrong with you? How did you put yourself in that situation?" (especially when it come to the parts about Ben and the mother). I did understood what they were going through, but I just couldn't empathize. (hide spoiler)] 
 I really liked it though, it took me a few days to read it: it made me feel things for the characters and when I picked it up, I couldn't drop it - that's how bad I needed to find out what was happening - which, for me, is the definition of a good book.