I had a hard time getting into this book. I think it was because of the déjà vu. Dan Brown is such a formulaic writer that I feel like I've read this book a few times before. It's not any different from his other books. He's used the same formula so many times that I was able to predict some of the twists in this one. Predictability takes most of the fun out of reading a mystery.
I usually enjoy the action-packed plots of Dan Brown books, but I had some issues with this one. The amnesia and its explanation seemed convoluted and gimmicky. I don't think the amnesia was really necessary. There were also a few too many history/art lessons. I like history and art, but constantly stopping the action to teach me something got frustrating quickly. I think this book suffered from too many ideas crammed into too little space. Cutting out all the unnecessary description may have helped. The ending was too drawn-out and preachy for my tastes.
The writing style got on my nerves. What's wrong with using He/She? The names didn't need to be repeated so many times. I had the same problem with the descriptions. The characters were described using the same phrases over, and over, and over. I lost track of how many times the author mentioned the provost's tan face. Despite all the descriptions, the characters were hugely underdeveloped.
Finally, the number of interrobangs was ridiculous. The characters spent the entire book shouting questions at each other and overreacting to everything. Even a ringing phone caused a bunch of interrobang-filled melodrama.
I was very disappointed with this novel. If you're looking for a good Dan Brown book, check out Angels & Demons.
The plot of that one is at least entertaining.