I remember thinking well of Angels and Demons. The Da Vinci Code, however, was, at every turn, horribly implausible. And Digital Fortress runs purely on Idiot Ball. The protagonist only distinguishes herself by being the person who carries the ball the least

EDIT: Also, Angels & Demons came up incidentally in a Facebook discussion between religion/English major friends of mine; Angels & Demons is nearly as jam-packed with completely false information as his other work. It turns out all of Dan Brown's books are Dan Browned