I have had Keldorn since the start of the game, and am in the Underdark and have done several side quests so I would disagree that he leaves soon after he joins. I haven't had a quest for him except to help the church, so I don't know that he's that interesting. However the dialog between him and other party members is interesting.
Not sure about Amoween since he seemed like too much of a weenie to me
|