Harley Quinn's Revenge is fun, but weak in a narrative sense.
A highly anticipated add-on to Batman: Arkham City, Harley Quinn's Revenge is going to be held up to some high standards. Unfortunately, in terms of both gameplay and narrative, it doesn't meet them.
Anyone who's played the base game knows that Arkham City is a Batman experience to be remembered. Throughout the game there's a very well-crafted sense of progression not only in terms of the story, but Batman's capabilities and the similarly escalating threats he has to face along the way. Harley Quinn's Revenge, as a rather short and stand-alone experience, has no choice but to throw you into Batman's end-game experience immediately, feeling a bit disjointed, especially for those who are returning to the game after months of not having touched it. In theory, playing as Robin would fix this issue, as the player is introduced to concepts at a brisk, but manageable pace, and brought back up to speed challenge-wise. But the immaculate pacing falls apart when it's rushed this quickly.
No sooner have you become familiar with all of Robin's tricks than Batman simply takes over again and the DLC ends. In many cases throughout Arkham City, you'd have a core principal of playing as Batman demonstrated to you, be asked to execute it, and then have opportunities to realize when to use it later on your own. Robin has two sequences that seem like they're meant to fit this mold, but they're either unexciting(using his shield to block automated turrets) or never used again after you're introduced to them(planting flashbangs on enemies via stealth and planting flashbangs on moving objects to attack enemies from a distance). It makes the whole DLC feel like a Robin tutorial with no actual Robin gameplay payoff. He gets a single stealth segment and then a single combat segment, and that's that. He is, however, fun to play as, which makes the whole thing still work pretty well, despite it's faults.
In terms of narrative, I don't want to spoil anything, but to be entirely honest there's not much to spoil. Anyone hoping for some sort of plot twist, sequel tease, or compelling characterizations is going to be dissapointed. The worst of it is the ending- you save the day, and Batman just walks off with Robin making a half-hearted quip. The end. Credits roll.
Was this worth the price of admission? Maybe. I personally enjoyed it, it was a fun two and a half hours and I can't say I regret buying it. But honestly, it's pretty skippable, and you see nothing new with Robin here that you wouldn't see in the challenge rooms playing as him- still a seperate purchase, if you want to do that, which seems dubious to me.
Harley Quinn's Revenge would be great DLC if it were any other title, but the quality bar set by Arkham City is simply so high that it feels lacking in every respect. Honestly, if you want to save the $10, you're fine just waiting for the inevitable sequel to get more Batman into your life.