At the time I read his FICTION books, I enjoyed them. I wouldn't know a tautology from a spare tire.
Dan Brown fiction is aimed at consumers that like a good story. Like James Patterson or Michael Connolly.
No intention by author or reader to test for literary style or other technicalities.
Regarding movies, I compare the critics to the viewers on Rotten Tomatoes and frequently, the viewers like movies better than the professional critics.