I agree with this post, Andrew. I love Ron Howard films (Apollo 13, A Beautiful Mind, and Cinderella Man are personal favorites) as well as Tom Hanks (Forrest Gump, Apollo 13, Saving Private Ryan, You've Got Mail, Catch Me if You Can, I could go on an on) but I found TDC very dull, and easily his worst performance in some time.
AT LEAST the screenwriter gave Langdon some lines to counter the silly history put forth by Teabing in the movie. For instance, blaming the Christians for atrocities against Roman pagans--without also mentioning the outright pagan persecution of Christianity in the 1st century AD--is just downright silly and transparent.
I will say, though, that one of the few redeeming qualities of the movie was that it got better as it went on...and the end of the movie was better than the end of the book.