I wasn't a fan of this book, it doesn't hold up to the standard of the rest of his writing. I felt the historical tid bits often out of place and that they weren't to do with the plot, just Dan Brown flexing his knowledge as a narrator. The twists were a little too wild, and I felt that when you reach the end, you get a sense of "what was the point?". He didn't have an actual effect on the end outcome of the story, or prevent anything. Almost felt as if Dan Brown actually agreed with the villains plan, and he was saying "it's evil, but it's necessary".
The twists and turns still keep you reading and the history is still fun, you will still enjoy the book, but it's standard is not up to the others in Langdon's storied life.