It's how incredible the web-slinging feels, and what you can do with it that adds a gameplay dynamic that's so different than any other game it's hard to put into words. And it's not that the game is based on the second Spider-Man movie, with all the stars, villains, and story developments that follow. The reason this is such a big deal isn't because someone else made an 'open-style' game or that you can wander or rather web sling around town doing anything you want at any time.
Critics and gamers alike have been calling for something like this since the day GTA III stole Christmas in 2001, and now Activision and Treyarch have done something wonderful. Although both Rockstar Games and Treyarch will probably cringe at the sound of the phrase, Spider-Man 2, the fourth game in Activision's comic-book based series, is, without a doubt, Grand Theft Spider-Man - a clear fusion of the ideas in Grand Theft Auto and the Spider-Man series.