Some are, largely the older ones. The newest books have lost something to me, and the related series feel like they're ghostwritten (they are ghostwritten -- but importantly, they feel like it.)
* The very old ones, Pacific Vortex, Mediterranean Caper, and Iceberg, are definitely dated. They also include some distasteful treatment of women and transexuals. The harsh (physically) behaviour to women seems to be Cussler's attempt to channel a Bond-like feeling. I don't like it at all.
* Dragon (if it's the one I remember) has an unpleasant rather racist feel. Like Crichton's Rising Sun, it's anti-Japanese.
* Raise the Titanic is what made him famous. Worth reading.
* The books Treasure, Sahara, Inca Gold are his absolute best. Big, thick, crazy adventure novels.
* Shock Wave I didn't like when I read it: something about the tone. I heard he had a personal tragedy before he wrote it, and maybe that affected the book.
* The books after feel increasingly ghostwritten, or at least churned out.
I enjoyed them as a teenager, and I was too young so some of the sexist or racist elements in the older ones passed me by. I read the Bond books at a similar age, and didn't understand everything I read. As an adult, re-reading, I disliked those elements strongly.
Yet, some of the stories are fantastic thrillers.
So: I'd recommend you avoid the ones that are distasteful, and the newer ones. But Titanic and those three others are worth reading. 'Big, thick, crazy adventure novels'. When you read them, you'll see why they keep periodically trying to make movies of his books.
