It doesn't sound like it's very entertaining fiction, from most of the reviews. Most reviewers give it only two out of four stars:
"A jumbled, joyless affair that neither entertains nor enlightens." IGN FilmForce Shawn Adler
"I’ll say it: It is anti-Jesus and anti-Catholic. Unintentionally though, it is a recruiting film for Opus Dei. Where do I sign up?" FilmsInReview.com Victoria Alexander
2/4 "The script explains everything twice, spelling out the big words three times, so that even if you've never heard of Jesus or Mary Magdalene you can still figure out this story." Combustible Celluloid Jeffrey M. Anderson
"Ron Howard and screenwriter Akiva Goldsman struggle mightily to cram as much as possible of Dan Brown's labyrinthine thriller into a 2-hour-28-minute running time, resulting in a movie both overstuffed and underwhelming." Newsweek David Ansen
""The Da Vinci Code" is essentially just another average Hollywood thriller. Nothing more." Sympatico.ca Angela Baldassarre
1.5/4 "You know a movie's a dud when even its self-flagellating albino killer monk isn't any fun." Commercial Appeal (Memphis, TN) John Beifuss
2.5/5 "Every time Langdon starts to educate Sophie, the urge to tune out is overwhelming." Las Vegas Weekly Josh Bell
2.5/4 "One could classify The Da Vinci Code as diverting, but it has sidestepped greatness by a wide margin." ReelViews James Berardinelli
2.5/4 "The movie is so nervous about offending anyone that it's hardly any fun." New York Daily News Jami Bernard
1.5/4 "Absent is the pure guilty joy of sequential puzzle-solving; instead of participating in the hunt, we're shoved off to the side as a couple of crashing boors do it for us."
Houston Chronicle Amy Biancolli
"The problem is the pace, which suffers when demands of explication force Howard to pull his foot off the gas." L.A. Weekly Greg Burk
2/4 "As a film derived from a book, The Da Vinci Code isn't a fiasco on the order of The Bonfire of the Vanities nor is it a triumph a la The Lord of the Rings. Instead, it's an acceptable but uninspired simulacrum." Boston Globe Ty Burr
2/4 "A film that never rises beyond the workmanlike to the inspired." Kansas City Star Robert W. Butler
2/4 "Too measured to be lively, too skittish to be provocative, too dramatically slack to be more than a ploddingly literal book-on-film." Groucho Reviews Peter Canavese
5/10 "[A] wishy-washiness and its general tonal flatness betray a clock-punching mentality the cast and crew seem to have adopted for its production." ReelTalk Movie Reviews Jeffrey Chen
2/4 "Ron Howard plays it too safe keeping fans of the book in line, objectors at bay and alienates anyone coming into the hype with thoughts of 'that's what everyone is up in arms about?'" eFilmCritic.com Erik Childress
C+ "... a jigsaw puzzle [that] turns out to be a lot less fun than you hoped it would be when you started piecing it together." Las Vegas Review-Journal Carol Cling
2/4 "Looking for that Holy Grail of blockbuster movies? Keep looking. You won't find it in "The Da Vinci Code," an overblown, bland ghost of the best-seller by Dan Brown. "