One of the things most difficult for a book to do is to deliver a sense of unease[1]. This book managed to provide that. The characters are strangely compelling, provoking sympathy and antipathy simultaneously. Throughout the story, there's the sense of waiting for more awful things to happen to the characters, some of which is of their own creation. The terrible and pitiable relationships in this family are well drawn. 
 (view spoiler)[I was not expecting this to be a book about the creation of a haunted house. The witch house on the edge of town that inhabits the nightmares of all the townsfolk. (hide spoiler)] That rather blew me away. I will be coming back to this book. 
 [1] Hierarchy of horror writing per Lovecraft: At its purest, horror writing delivers a sense of unease, dread, and tension. Below this is fear-literature, followed by the literature of mere physical fear and the mundanely gruesome (e.g. jump scares and gore). 
 Or per Stephen King, "I recognize terror as the finest emotion and so I will try to terrorize the reader. But if I find that I cannot terrify, I will try to horrify, and if I find that I cannot horrify, I'll go for the gross-out. I'm not proud."