hmm, I've never read Uncle Tom's Cabin so i can't make any judgement calls as to its quality. but one of the reasons people write is to convey messages, beliefs, and ideas to other people: if a book manages to successfully get the author's message across to others than that book can't fail, in a sense, because it fulfilled the author's purpose.

on the other hand, even if a book's message is clear, that doesn't mean the story was told in a interesting or sophisticated or entertaining manner. so from a 'personal enjoyment' perspective, a book could 'fail'.

...actually there was a recent post on bookfails that sort of discussed this. a poster said Bram Stoker's Dracula was overrated and boring, and some others said that even if she didn't find it very entertaining personally, that didn't mean the book was overrated, because there are many other reasons Dracula is considered an important book in literature when considered from a social/historical perspective.

basically i just wish people would understand that people read and write books for more than just entertainment, and that sometimes, being difficult or unenjoyable is an intentional choice on the part of an author.