It wasn't a pre-order bonus, just extra content on the PS3. However, it was relegated to the Challenge Rooms, and the GOTY version adds that content (Challenge Rooms and the Joker as a playable character) to the 360 version.
I want the 360 version, partially because the 3D piques my interest, but that's still too gimmicky to drop the money on the game for just that; simply put, the 360 version looks better.
Here are some good screen comparisons between the PS3 and 360 versions. Plus, for most games, I prefer the 360 controller, and now that I have a shiny new 360 Elite and not the gimpy launch-day machine, I'm gaming far more on it. The PS3 is still the Blu-ray/DVD player, and Phe games on it (the smaller controllers are more comfortable for her tiny, tiny hands; plus, she loves
LittleBigPlanet and
Dragon Age: Origins, which we bought on the PS3), but the 360 is my primary game box.