Peter, did I read that correctly, or did you really hint that Huckleberry Finn was somehow overrated? I remember reading it as an entertaining adventure novel as a twelve year old and then again as a young adult. They were two very different experiences. As an adult it made me laugh on nearly every page - it is worth reading for the asides alone. "He charged nothing for his preaching - and it was worth it." However, the central themes of the book are weighty ones which are integrated cleverly into an entertaining story. It is a serious book as well for several different reasons. My favourite paradox is the fact that Huck believes himself less moral and less intelligent than the rest of society. He constantly proves to everyone except himself that this is untrue. Somehow these days, being entertaining seems to disqualify a book from having any real merit. Give me Mark Twain's readable, funny prose against Dickens's stodgy, stiff, Victorian moralising any time.
I should add that two other works which really shook me up when I read them were Somerset Maugham's "The Razor's Edge" and Shakespeare's "King Lear" -which still scares the daylights out of me!