The De Vespe Conspiracy features the arrival of Princess Aurelia De Vespe, daughter of the De Vespe family and long-term enemy to the D'Orsays, to the island of Teer Fradee. It adds a new area with a new, 2~3 hours long quest in it, with some entertaining new scenes and a compelling antagonist. At the end of the day, though, it's more of GreedFall. You're likely to enjoy this as much (or as little) as you enjoyed the main game.
Solid little piece of DLC. It takes you to new small map (though slightly bigger then the maps in the base game. There you get a cool little story that takes place in the middle of the base games story. It also adds in some new weapons and armor to find and it even has a slide at the end of the base game to show how your choices impacted everything which I liked.