What I think:
First of all, I love the title and cover of this book. Although at first the proportions of the girl on the cover looked a little off. She looks younger than she's supposed to be in the book.
But anyway, I really liked the book. It reminded me of all the ghost stories told at parties, on monday mornings on the radio (in my country) or by my mom and grandma. It was well-written, somehow plunging into the action immediately while still managing to be introductory at first.
The characters were likeable and interesting. It was nice to read a book from a guy's POV for a change. I thought I wouldn't like that, but I did. Cas, the guy, was smart, honest, no-nonsense and downright interesting. He also showed a pretty cool sense of humor, which I didn't expect, but always love. Then there was Anna. I loved the multiple layers to her. She was a vengeful ghost, a sweet innocent girl and a victim that at no single moment acted like one. She could be mistaken for fragile and weak at a glance yet there was no doubt about how strong she was. She was inspiring and was written in such a way, described in such a way by Cas, that her evil part could almost be dismissed. Almost.
The pacing was nice, something I haven't seen a lot since reading Dutch teen books when I was younger. It started out slowly (which in this case is good and you might not even agree, because the start was interesting) and lead up to multiple climaxes which were far enough in between for me to catch my breath and recover before the next bomb hit.
It's definitely different from certain books I've read recently that keep throwing bombs at you without giving you so much as a miniscule break. Let me tell you, although that definitely gives a rush, it also takes a lot out of you. So I'm definitely happy this book isn't like that.
In short, this book was a great read. The "peak events" were all definitely worth waiting for and reminded me of something from the tvseries Supernatural. Actually a lot of the book reminded me of the tvseries Supernatural. And anything that reminds me of Supernatural is definiely worth reading.