As the other reviewer suggested, I enjoyed this one quite a bit and had not previously read the book. It can probably best be described as an interesting cross-breeding between Da Vinci Code and the Indiana Jones flix ... there's even a funny line early in the film where Tess is described as a "female Indy".
I think what impressed me most about this one was my surprise at finding, in the credits, that it was made for TV. Back when those first started, when I was teaching little Noah how to walk, they were notoriously dull and cheaply made, but this one's definitely got major-studio quality in it. It's a little "lighter" than Da Vinci Code, but definitely much more thought-provoking than the Indy adventures. By all means give it a try.