I know a number of people who love this book, and I can see why. It's an atmospheric and creepy read, very much inspired by traditional ghost stories, and if that's what you're looking for in a middle grade then I do recommend this. 

Unfortunately it's just didn't quite work for me personally. I liked the main character but every other character felt underdeveloped - I had expected more of a focus on Harold as he's mentioned in the blurb, and I really wanted to see more of Aveline's growing friendship with him as well as her relationship with her aunt. I think on the whole I'm just not fond enough of ghost stories for that to be the entire plot and focus of the book, I needed more. 

It's not a book I particularly loved, but I do think it's a decent horror story and if the blurb sounds interesting then I recommend giving it a try.