The BBFC has rated the DS GTA: Chinatown Wars with an 18 certificate, with strong language/drug references.
The game marks the first DS title to receive a rating that high, as the strong language and violent nature from the past games doesn't seem to have been toned down for the release. The listing also states there's 168 minutes worth of in-game cut scenes to watch through, giving hope for a meaty story in the tiny cartridge.
Thanks to QJ.net.