While it'll be interesting, perhaps most of all, to see how South Park: The Game moves and how you interact with things in the world, it's certainly refreshing to hear that a license holder decided on the developer they wanted to work with and have a heavy hand in the development of the game.
That's what's happening with South Park: The Game, Obsidian Entertainment, and Matt Stone and Trey Parker. The creators themselves even went hands-on with the game and were surprised by how much the game itself looked like the paper they work with every week.
When I was at Obsidian for Dungeon Siege III earlier this year, Studio Head Feargus Urquhart was really excited about working with a specific license, but wouldn't say what it was. It might not make sense at first, but something tells me South Park: The Game will be interesting to say the least… buggy, but interesting.