Robin isn’t that popular compared to the Batman. In fact, the arc A Death In the Family had the Robin with the real name of Jason Todd die in an explosion by popular vote several years ago (but it was a very close vote). However, Robin in Arkham City has taken levels in badass.
Paul Crocker had said “Everyone knows who Robin is, we wanted to, I guess, reinvent Robin so that he’s one bad-ass kid. So people don’t go ‘Oh robin, he’s no good to fight with’.”, according to Crocker, Robin can “beat the crap out of anyone” to put it into his words.
In an interview with ComicBookMovie, he said “He’s got a full outfit, he’s not just a re-skinned version of Batman. Every time we had a character enter a challenge map or enter the game we think, ‘How can we make this character unique and as good as Batman?” Robin is often a bit of a scrappy in the Batman series for whatever reason, but him being a competent ass-kicker this time around is quite a difference.
If you’re wondering which Robin it is, it’s Tim Drake, who is one of the more popular Robins. I’m not a huge fan of Batman so I don’t know the full continuity outside of a few books.