Although Conclave does require an unusual amount of hard work on the player's part, as well as the patience of a saint, the expansion is still mostly worthwhile (many of the bad changes were in the free patch, so there's no way to avoid them without reverting to a previous version).
It's really sad to see scores slowly slide down like this, but with Crusader Kings II seemingly starting to get stuck in a rut due to a lack of a desire to release things like new maps (hint: China/Japan or a fantasy-style alternate campaign), there wasn't really anywhere for Conclave to go that wasn't 'sequelitus.' As a content patch it would get an A, but as an expansion? Sadly, not so much.
Crusader Kings II: Conclave represents the best incarnation of the veteran grand strategy title from Paradox Development Studio, a great experience for any player who loves history and wants to explore the many what if situations of the past.