I thought it was significantly better than the previous book, and enjoyed the story. The multi-layered plot did get mildly annoying at times, especially as it was obvious almost from the start who the Missing Sister really was.
But I also feel very cheated. I think like everybody else, I thought this book would finally solve all the mysteries. I was astounded to have got through 800 pages only to discover: “To be continued” in an eighth book, to be published Autumn next year.