Agree with Rekstout. It's basically a bog-standard airport thriller with terrible characterisation, a baddie it's possible to spot from his first appearance, and some ludicrous plot devices. For all that, the esoteric knowledge is pretty interesting and for me was the value in the book. Don't get me wrong; I enjoyed it immensely, but it's hardly great literature.
I could certainly see that it's 'Foucault-light' - it did occur when I was reading it, but Eco is superior in virtually every way. (That said, the first chapter of Foucault, when he's stuck inside the museum, is an exercise in frustration! I thought I had a reasonably large vocabulary until I read that!)