National Treasure gives a new meaning to the phrase "living history", and it really is something thoroughly amazing for a work of historical fiction. It is entwined in a gripping mystery which uses as reference points, things you can find in your pocket, like a dollar bill, places you've probably been to like the national archives, the mall in D.C. etc, making for a truly interactive experience.
Complaints about lack of character depth in National Treasure should be made keeping in mind the context in which Bruckenheimer (did i spell that right?) made the film. If you're Jerry Bruckheimer, you went from being a very hot commodity after making a $285 million-grossing film, Pirates of the Caribbean, to making King Arthur, a flop, and you want to preserve your reputation as a commercial success. Therefore, you're #1 goal is to get people into the theater and what's gonna get them there is the plot. The movie is all plot-centered and even though Nicholas Cage might have won an Oscar way back when the truth is that most of his movies "gone in 60 seconds", "snake eyes", "8 mm", etc, are not films you go to expecting character development.
I don't think they were aiming for character depth: No one was going into this film thinking they'd snag an Oscar or golden globe nomination, Not that you shouldn't want to have a challenging part to want to act in, but I was pretty fine with the limit on character development because the plot was cool enough. The one thing I can say was, at the very least the characters were self-conscious, for example, the Abby Chase/Ben Gates hook up we could all see coming from miles away, but evidently so could the screenwriter so he gave Ian the line "well, you got the girl at the end" cause it's so blatantly obvious.
Also, the plot is absurd in itself, stealing the declaration of independence? And it's actually quite a wonder in itself that the movie presented a historically accurate, seemingly plausible and thoroughly engaging plot out of the circumstances that in no way dumbs down to the audience. Making the plot work in itself, deserves credit.
The film played to its strengths well.