The PSP version features updated graphics, which are no longer cel-shaded, thus sporting a more "classic" look akin to previous games in the series (however, cutscenes are stylistically identical). Mini-games (such as drawing tattoos, unscrewing the car and boom panels) have been adapted from their touch-screen functionality to simpler, QTE-like mini-games. The PSP version also features extra missions and exclusive radio stations not found in the Nintendo DS version. However, PSP multiplayer supports only 2 players.
http://en.wikipedia.org/wiki/Grand_Theft_Auto:_Chinatown_Wars