An excellent and thought-provoking book. This is the book that "The da Vinci Code" wants to be when it grows up. If any of your friends begin enthusing about Dan Brown, make them read this. If they can't or won't, then unfriend them.
Eco hits it out of the park with this one. As in-depth and detailed as "The Name of the Rose" is, "Foucault's Pendulum" is better. Brilliant, alive, and filled with so many details and symbols that only a semiotician could have written it. An excellent companion piece not only to "The Prague Cemetery" (which is like a mini-version of this tale), but to Eco's studies of aesthetics in the Middle Ages, as well. Just read it.