The funny thing about The DaVinci Code is that it wasn’t an immediate hit. Barnes & Noble had heavily bought into the book somehow. If I remember correctly, they had some sort of financial stake in it beyond just selling it in their stores. It took months to over a year for the book to take off in which time they were sending our small store cases upon case of the book. We would put out full tables, endcaps and floorstacks of the book not selling a whole lot of it. We would send cases back to the warehouse only to have them show right back up. Then, something happened and it really caught on.
I read a couple of his books. They get to be a bit formulaic but are decently enjoyable. To me, he’s somewhere between Michael Crichton and Brad Meltzer.