Jack's 55th Birthday has a really funny aesthetic, but that's about it. 21 is a game of blackjack with a bloody twist, nothing special but still fun enough. The real meat of this DLC though is Sisters, where we can see how the Baker family got infected and I must say, it's pretty chilling, even if it's not really that necessary, as you can deduce how it went by context in the main game. Again, I wouldn't say it's worth buying it, but if you have the gold edition give it a try.