Never change a winning team, that's probably what Dan Brown is thinking with this series. I know that series often tend to get a bit predictable after a number of books, but this is just the third instalment! (After this one, I never bothered with Inferno)
There is one mayor change though, instead of running through Europe like a headless chicken, things are now set in America. This means of course that plot theories can no longer date back to (pre)-Medieval or Renaissance times. What a reviving change(!).
I guess that if you don't have a problem with obvious formula writing, this isn't so bad.
Note: I read a Dutch translation of this book