It is true that Activision is releasing two versions of the game for the PC, one rated T(een) and E(veryone). The E version is the one that the game demo is based on. This is a very watered-down version of the console game and doesn't allow free roaming, non-linear gameplay. You also can't swing from anything, only web swing targets that hang in mid-air. This version of the game is so crappy because its targeted at a younger audience.

However, the T version is supposed to be a clone of the console versions, allowing non-linear gameplay similar to the Grand Theft Auto franchise. You are able to follow the plotline as you wish, or you may opt to go web-swinging or saving people at random. Hope this helps