It seems Rockstar Leeds did everything right with Grand Theft Auto: Chinatown Wars on DS - everything, it seems, except give it to an audience that would fully appreciate its charms. Far from a poor seller, it nonetheless seemed a relative disappointment compared to the stellar sales the franchise is used to achieving on other platforms.
That's not the reason for bringing the game to PSP, though. Rockstar always planned Chinatown Wars as a handheld GTA, not a DS GTA. Playing through a fairly complete build of the game in the developer's swanky Fulham office, that becomes readily apparent.
Those wondering how a dual-screen experience with heavy touch-based elements could possibly survive the transition to a single screen with traditional controls can stop worrying.