I think I figured out what annoys me about Dan Brown books. They don't think much about the reader's previous reading habits or general knowledge. Every minute thing relating to science or religion is overly descriptive and semonized until the reader is blue in the face.
I almost started giving Brown the benefit of the doubt, since his protagonist is a university professor, and, as such, he may tend to sermonize and act superior to those (non-academics) around him.
Regrettably, the coup de grace plot twist in chapter 120 (or thereabouts) is hardly that big of a shocker. However, when the story goes back to tell you what the author didn't tell you while things were happening, really are a shocker...at how badly that's done. Again, my huge pet peeve when reading is that an author's main duty is to show the reader, not tell him/her.
Thankfully, I only have 2 hours left of listening to do for this audiobook. And *sigh and eyeroll* I'm sure Langdon ends up sleeping with the heroine in this book too in the very end.