This is 3rd most important DLC to pick up for CK2 (after Legacy of Rome, and The Old Gods)
This DLC gives you a significant advantage when playing. You can borrow 300g from the Jews, then expel them for 200g more. At the start of the game you instantly have 500g.
Bishop/Cardinal mechanics are basicly worthless.
-Biggest problem I have is that the Pope is always perfect, and all your bishop vassals will pay tax to him.
-Pope will give you money regardless. Whether you cared to give vote him or ignored the mechanic altogether. Basicly New Pope = gimme that money. Leave your councillor bishop improving relations with pope, all game. You will make 5000g easy.
-minor actual control over the Papal state. Dynasty member will give you the same amount as non-dynasty with the same traits.
Religious events are basicly 30gold for 30 piety, and 20% chance of drunkard or 30% +1learning.
Jewish characters could be fun to play, but you can't borrow and expel Jews for 500g... making them weaker then any state in the game with a "modern/reformed" religion