I really loved the beginning of I Capture the Castle, but did not like the direction it took, or the ending, at all. I too try to finish books even when it is clear that I don't like them--I don't know why, really--I guess I just don't like leaving them unfinished. The book that often appears on these lists (although it is not on this one) that I am currently trying (and failing) to read is A Confederacy of Dunces. I've heard it's brilliant, but so far I just find it irritating.