I just finished reading the article about the new Warlock's cave cards and I think they will be a good addition to the game. Granted some of the new quests seem ridiculously easy (visit the Cursed Glade) and others surely are harder, but I guess we had that with the old quests as well.
The suggestion to speed up the game (The Warlock Quest Cards can also be used to speed the game along: at the start of the game, each player draws one card at random.) is pretty intreging to me...but maybe could use a little wrinkle. If you decided to go on the random choosing route at the end of the game maybe you could only be able to select from the 4-6 "hardest" quests.