Dante's Inferno by Dante Alighieri, and Wind and Shadow by Kathy Tyers.
Dante's Inferno is actually interesting, which is surprising coming from a book that is recommended reading. Though I find the "helpful" hints on what the text "actually" means both frustrating and aggravating. Frustrating, because they're usually opinion, having no bearing on the text in question and reading a lot of stuff into the text that just isn't there (unless a few thousand words and meanings are lost in translation for each canto), aggravating because they also often contain historical information needed to understand many of the peoples referenced, and thus I am forced to read them.
Wind and Shadow on the other hand is a bit disappointing. It's a continuation of one of my favorite speculative fiction stories ever, and the author seems to have changed her thoughts over the years; elements which, in the first part were good, are now given much, much darker connotations and evils. Characters the first books were based on are either redundant versions of themselves (meaning that huge spiritual change they went through earlier apparently never happened), not present, or just "there" to be there.
So I am torn.