I'm struggling a bit with this topic. I do have to read a bunch of books that assigned for work, and sometimes these books surprise me because I love them more than I expected. Netherland by Joseph O'Neill, for example, was much better than I'd anticipated for a post-9/11 novel about cricket, written by a guy I'd never heard of before. I hope that I'm pretty neutral about books before opening them (except for Twilight).
One book that definitely surprised me was Look at Me by Jennifer Egan. I'd never heard of Jennifer Egan before this book was nominated for the National Book Award. If I recall, it was a year with several nominees I didn't know, and I confess that for some reason I was confusing Egan with Susan Isaacs (the woman who wrote Shining Through). Don't ask me; my brain does odd things sometimes. I just looked it up, and the 2001 NBA nominees introduced me to Dan Chaon and Susan Straight too; the other finalist was Louise Erdrich, and the winner was Jonathan Franzen for The Corrections. Anyway, I couldn't imagine how the author of a book that was turned into a movie starring Melanie Griffith could be an NBA finalist (because, as I said, I thought she was Susan Isaacs). I really went in thinking that Look at Me would be the biggest travesty in awards nominating history.
I'm an idiot sometimes. Look at Me remains one of my favorite books, and Jennifer Egan is one of my favorite authors (and now a Pulitzer Prize winner). I love this book so much that I'm willing to guarantee that you'll like it too. If you hate it, tell us, and Gianna will bake you cookies as an apology for my confidence. [Gianna will not bake you cookies.]