The Wruthering Heights thread gave me this idea. What was the most difficult book you ever actually managed to wade through? For me it was Crime and Punishment. I enjoyed it enough to keep reading, but at times it was a chore. In the end it was worth it.

The most difficult book I did not finish reading? A Portrait of the Artist as a Young Man by James Joyce. And I came only within 20 pages or so of finishing it! By that point, I no longer cared.

Also unfinished: Moby Dick, Bleak House (alhough I have enojoyed many of Charles Dickens's books), The Red Badge of Courage and many other fine books, I am sure.