Well, all you do is choose it from the menu and you play ~2 hours in the Steel Mill sector of Arkham. You will switch back and forth between the Dynamic Duo as you stop Harley's...umm...Revenge. It's not a bad play, but it feels like you're basically just playing Batman's first two hours, only now you're playing as Robin. And if you already got the Robin Challenge Maps DLC, then you've already had a taste. There are some cool moments, but it's light on the puzzle solving/exploration/story that made Arkham City great. It honestly feels like Arkham Asylum. So, not a bad thing.