As a South Park fan, this game is exactly what I've been waiting for. It looks and feels EXACTLY like the show, and Parker & Stone have been heavily involved from the get-go, so the writing and voice-acting is very much up to scratch.
You start off by designing your own character, the "new kid", and learning how to battle in typical South Park fashion, with Cartman as your guide. The battle system is straight forward - the game is very much a turn-based RPG, and reminded me of Paper Mario or Costume Quest. It's simple enough, but there's plenty of items to collect, loads of sides-quests and an incredibly detailed town to explore.
The game is incredibly funny, too. South Park has never been just toilet humour. The gross-out, over the top, "shocking" stuff is there, but that's not what makes South Park great. Stick of Truth is overloaded with parody, and I particularly enjoyed the tongue-in-cheek digs at various video-game tropes. In the console version there are certain elements that are censored, but I feel like I might have enjoyed the tongue-in-cheek "censored" screens more than the over-the-top stuff, and certainly don't feel I missed anything important.
If you don't like South Park, you should probably stay away. But if you're a fan, I would urge you to pick this game up, even if you're not normally one for turn-base RPGs.