It took me a good 150 pages to really get into this book, but eventually I ended up enjoying it quite a bit. It has a fun, quirky story with likeable and interesting characters. I would say the book borders on comedy (it certainly embraces silliness on occasion) without being laugh out loud funny. It's very fast paced and I read it quickly. 

I did read the book without having read the earlier books set in this universe. It's not a direct sequel so I wasn't confused about the plot, but there were any number of references to characters and events I presume appear in the St Mary's series, and I suspect someone who has previously read the series may get more out of this book. 

I also have to mention the art deco style cover, which is absolutely gorgeous.