As usual, Douglas Preston and Lincoln Child confirm their great ability in writing cool, well-conceived page turners.
In this book in particular, a lot of details about some of the characters are unveiled, and the "Pendergast Trilogy" featuring Aloysius vs. Diogenes finally comes to an end... and what an end!
Apart from the praises for the writing style and action scenes, for the characters and the mood, another point I found particularly strong in this book was the obvious amount of research the authors did. I am Italian, and the small details, for example the streets of Florence, or the cuss exclamation of a Carabiniere, or even the cell number of a bus driver (which uses a correct prefix for an Italian cell phone, no fake "555" number) all prove that they really went into research for the book.
Also, the frequent sentences in Italian are correct and do make sense this time (unlike some of their previous books where the sentences were dictionary-translated and light-years from what a "real" Italian would say).
All in all, a fantastic book, definitely well worth it!
If you appreciate Preston and Child's novels, don't miss this one, with a single caveat: for maximum enjoyment you will need previous knowledge of facts and characters, so reading the other books (at the very least Brimstone and Dance of Death, ideally quite a few others) is *strongly* advised.