Decent buy on a sale
This DLC gets you some extra in-game currency and lockpicks and two additional weapons. While it's a better kick-start, as you progress through the game, you realize that it isn't much. Weapons are nice, though.
I bought it on sale and I recommend you do too, even if the base price isn't that high, you can complete the game and whiteout even knowing it exists. But if you're a fan of Bioshock Infinite, at the expected discounted price (around 1-2$), it's a must-buy.