I read Name of the Rose first, and loved it. I liked Foucault's Pendulum at least as much, maybe more. Baudolino was excellent. I never could get into Island of the Day Before.
But The Mysterious flame of Queen Loana was curious: I was captivated by it as I read it, and even stayed up too late a couple nights. But it was slow going, and for some reason, after I had to set it aside very briefly, I didn't return to it. Is there a word for that? Something that's fully engrossing until one is distracted from it, at which point one doesn't return to it?
(I also heartily recommend a book of Eco's essays called How to Travel With a Salmon. Several are truly hilarious.