OK, well, we guess we could tell you that you can run the PC version in stereoscopic 3D with GeForce 3D Vision glasses. There are also new costumes and an improved mercenaries mode with three times as many not-zombies to murder.
See, that other stuff was barely enough for a paragraph. However, this has now become a not inconsiderable block of text, and we feel perfectly comfortable moving on, confident that you, the reader, have gotten your money's worth. Good day.