I started this book last year while visiting Paris. I try and read books relevant to the places I visit but on this occasion it wasn't a good choice. I found it very hard to 'get into' the book, so I abandoned it until a month ago. I was then able to read the rest of it and enjoy it although not as much as his other books.
The history of Paris is fascinating and it is worth reading, maybe start before you arrive in Paris! The first third of the book is the hardest, after that it's ok.