Harley Quinn's Revenge is Rocksteady's downloadable epilogue for Batman: Arkham City. Unlike their previous offerings where players download challenge rooms or playable characters, it is narrative-based content with limited open-world exploration that lets the player control Batman and Robin. Despite what it delivers, it was not enough reason to justify a $10 price tag.
As the final chapter in Arkham City, HQR is anti-climactic. Harley Quinn is out for revenge after the events of the main game, but nothing gets accomplished. The DLC ends in the same position it began, fails to build off the dangling plot threads from the main game, nor does it bring any new major developments to the table. Players can avoid purchasing the title and not miss out on anything.
The highlight of HQR is playing as Robin outside of the challenge rooms. Roaming around the rooms and hallways feels quite different than being confined to one map and shows how the developers put just as much effort into making his moveset and gadgets as they did with Batman. Being forced to switch back to Batman after progressing through the DLC feels like a letdown and it could've felt much more focused if Robin was playable for the entire time. Unfortunately, players can't play as Robin during the main game like they could with Catwoman because HQR is listed under its own separate option in the game's menu instead of being integrated into the main game like most post-game DLC. Most players will take one or two hours to complete if they don't try to go after all the trophies and achievements, and other than that, there's no real reason to play it more than once
Harley Quinn's Revenge ultimately fell flat. The cost is not worth two hours of content and a haphazard attempt at expanding the game's narrative. Anyone who is interested in playing is better off waiting until it goes on sale before buying it.