In this old interview, Stephen King talks about the importance of opening lines in books. Personally, I'm not sure they are that important. I never judged a book by its opening line. The first chapter - yes. Sometimes even the first page or two. But one line or one sentence? No.
What about you? Are there books that hooked you by their opening lines? Have you ever stopped reading because you didn't like the opening line? Do you have a favorite opening line? (Moby-Dick doesn't count; everyone is quoting it.)