The Arkham Asylum portion includes Trioviz 3D vision, and the four challenge maps: Scarecrow Nightmare, Crime Alley, Totally Insane, and Nocturnal Hunter, while the Arkham City portion includes the Harley Quinn Revenge missions, the Catwoman pack, the Nightwing bundle pack, Robin bundle pack, Challenge Map Pack, plus these 12 skins: 1970s Batsuit, Year One Batman, The Dark Knight Returns, Earth One Batman, Batman Beyond Batman, Animated Batman, Sinestro Corps Batman, Long Halloween Catwoman, Animated Catwoman, Animated Robin, Red Robin and Animated Nightwing.
No word on a PC version of the bundle.