For a book on Jack the Ripper, it doesn't really have much on the man himself. There are quite a few references and the build-up of suspense is pretty good but at the end of the day, I wouldn't really call this Jack the Ripper book so that was quite a disappointment. 
 Maureen Johnson's writing, however, is not a disappointment. She writes Rory with such humor and wit that she's such a charming girl to fall in love with. I like many of the quotes she come up with, like how Americans are presumed to be armed and that she isn't used to drinking tea in England because back home in the South, she's used to drinking iced tea. I like the fact that Rory makes friends as well, but they're not written as token characters. They do have a certain use to the plot and they were fun to read. 
 I was disappointed with the whole "secret ghost police of London" revelation as well. The idea definitely had a lot of promise but I had hoped for a bigger team that what was introduced in the book. I mean, maybe 4 - 5 members, that's not really a police. It's laughable really. The mystery of Jack the Ripper coming fared much better and I did like the suspense built around it. I liked how he came after Rory as well and it made for good drama. 
 The book ends on some sort of a cliffhanger that suggests the possibility of a sequel. I certainly wouldn't mind reading but I think it definitely needs to up the ante from now on.