Robin will be a playable character in Batman: Arkham City's challenge mode, but he will not be playable in story mode as Catwoman is. Robin is an exclusive pre-order download for Best Buy, as stated on their website, but it's not clear if The Boy Wonder is a timed-exclusive or if you'll only be able to get the content pack from Best Buy.
The Robin content pack is more than a re-skinned character; it comes with Robin-exclusive gadgets, special moves, two new challenge room maps and a Red Robin costume. I'm pretty sure the Red Robin costume is a furry costume from the restaurant chain. Don't quote me on that though.
The Tim Drake Robin DLC pack will be available for the Xbox 360, PS3 and PC. Batman: Arkham City will be released on October 18.
Many gamers have been very unhappy with exclusive DLC, as seen with the planned boycotts of Battlefield 3. Day 0 DLC and retailer exclusive DLC is hardly a new thing, but it's not popular among gamers either. How do you think gamers will react to Robin being a Best Buy pre-order exclusive?
I'm just going to say what I know you're thinking. Robin looks like Cole MacGrath.
Source: Best Buy