Calling Hardinge a YA novelist is something of a misnomer that, I think, is a result of her writing young women as her main characters and specializing in a genre that had its heyday about 230 years ago. Her books are certainly modern and feel as though they were written by a contemporary author, but she is a gothic novelist of the highest caliber. Her work is shadowed, gloomy, haunting and haunted, and centers on a young, vulnerable female protagonist trying to find her place in the world without the world destroying her first.
Because Hardinge is a 21st century, she often bucks the trend of the marriage plot and her heroines are often capable in a way that your average 18th century gothic heroine is not (with exception).
But Hardinge manages to give me the gothic shivers every time. I love it.
I'm not sure this book was as revelatory as "A Face Like Glass", which is the first book of hers I'd read, but her approach to possession and ghosts is genius and the way she tells the story is just perfect for the genre.