I have yet to read the book (so many things I do not have money or time for) but this quote sums up what I have read about it:

“What Dan Brown has given us is, literally, a sensational story.
He has taken broken pieces of the truth and woven them into a thrilling narrative full of holes.”

The book is fiction that wants to present itself as fact. Worse than that, it is deliberately false anti-Catholic propaganda that tries to present itself as truth. I am certainly not going to buy the book but I may read it.