Angels & Demons & DaVinci, Oh My

So Angels and Demons opened big this past weekend, zooming to the top of the charts, and already one critic has embarrassed himself by slagging the movie for a scene in which Tom Hanks escapes from a sealed glass room containing no oxygen by pulling out a gun and shooting the glass.

Just for reference: gunpowder is a solid propellant complete with oxidizer. It does not require an external air supply. Gunpowder-powered firearms will function in hard vacuum, underwater, in rooms filled with Halon gas, etc., etc. So the movie is right, and the critic is an ignorant nitwit.

But never mind that now. Today's topic is Dan Brown, and my question is a simple one: what is it that he's doing that he does so well?

Because I found The Da Vinci Code to be an unreadable slog. Never could muster the will to crack the cover of Angels and Demons. And then there's Digital Fortress:

When the NSA's invincible code-breaking machine encounters a mysterious code it cannot break, the agency calls its head cryptographer, Susan Fletcher, a brilliant and beautiful mathematician. What she uncovers sends shock waves through the corridors of power. The NSA is being held hostage...not by guns or bombs, but by a code so ingeniously complex that if released it would cripple U.S. intelligence. Caught in an accelerating tempest of secrecy and lies, Susan Fletcher battles to save the agency she believes in. Betrayed on all sides, she finds herself fighting not only for her country but also for her life, and in the end, for the life of the man she loves.

In one sense I can't help feeling a certain paternalistic pride, in that the memes of cyberpunk have grown up and gone from being the stuff of bleeding-edge sci-fi to being the stuff of formulaic by-the-numbers potboilers in less than thirty years. In another sense I fear I am emitting the strong and unmistakable scent of sour grapes, for even the worst of Mr. Brown's failures sell better than even the best of my best-selling books could ever hope to sell.

But on the gripping hand, I remain unable to finish reading Digital Fortress, because every time I try—and I have tried many times—I end up having to stop because I'm laughing so hard. And it's not intentionally a comedy.

Ergo, today's question. Dan Brown: good, bad, ugly, or indifferent? And how does he do it?

Your thoughts, s'il vous plait?