If you pre-order Batman: Arkham City from GameStop, you'll get access to Robin as a playable character in a set of challenge areas (Edit: My apologies for the confusion. In North America it's a Best Buy exclusive. Elsewhere, Robin is at GameStop). If you want to see if the Boy Wonder's worth your time, check out this video. It'll show you everything you need to know.
Arkham City is almost upon us and we're pretty damn excited at Destructoid. Personally, I'm most eager to see if Scarecrow's actually made it in.