It has a very GTA-ish feel to it- controls, missions, storyline, etc- all use the GTA formula.
The fighting system in the game is improved, and some moves are downright hilarious. Wedies, swirlies, trash canning,- it's all there.
You start out as the new kid on the block that everyone hates. You'll get bullied frequently.
The main object of the game is to earn sway and respect from the various factions (clicks) at the school- Nerds, Preps, Greasers, Jocks, and Townies. In the beginning, they all hate you- and try to beat you down.