At first glance the books are about 500 pages long each which takes time to read, but it is definitely worth the time.
The detailed descriptions that fill the pages to bring the places and events of the past to life are beyond fantastic; you can literally see the characters of Leonie, Anatole and Isolde (Sepulchre) sitting and playing cards or Audric Baillard (Labyrinth) spending the centuries waiting for Alais (Labyrinth) to turn up. Everything from the nineteenth century dresses to modern day hotels is portrayed in a way that you can believe the events really did happen.
A huge amount of research on each individual aspect of these novels has been undertaken, which is evident in the thorough knowledge and descriptions given. What I particularly love about the books is not just the combination of historical investigation (history nerd here), France and magic, is that the central underlying theme is love; whether it's between family, friends or a couple. Okay end of gushing. Basically, it is a great series of books, anyone who loves history or even just likes tales of mystery and adventure will also love them.