Dan Brown seems to be losing his mojo. Most surprising is that his usually infallible pacing is off. (The last several chapters are a torrent of too quickly tied loose ends and instantaneous character transformations that go beyond any possibility of credulity). You might like this book if you enjoy every other sentence being in italics.
One idea I had while reading was that instead of writing "Langdon remembered..". and then dumping a few paragraphs from a wikipedia article, Brown had instead donated each time a hundred dollars to charity, some charity would be very rich indeed.
On the plus side, it's a page turner and won't take long to read.