Being the first GTA game on the DS, it's very good.
The game is once again set in Liberty City, Where Huang Lee, a triad who has decided to return to Liberty City to return his father's heirloom sword to his uncle. When he arrives, he is wounded and dumped in the water by a group of assassins, who think he is dead. After escaping from the car, he goes to his uncle's place and tells him he lost the sword.
The area is very much based on GTA IV's Liberty City, except Alderney is gone. Despite this, the city is very big and complex. Most of GTA IV's locations such as The Strip Club, Times Square, and the Theme Park appear in Chinatown Wars. Gameplay is pretty much everything you'd expect from a GTA game.
You complete missions to earn money and explore a huge free area. There are some new features, including a replay mode which lets you replay previous missions.
There are even minigames that make use of the touch screen feature, such as a drug-dealing minigame where you have a selection of drugs to sell or buy. Once you have bought or sold your drugs, you can after kill the drug-dealer just for the hell of it.
Breaking into a car gives you a touch screen minigame where you have to hack the car system so the alarm doesn't go off. There are tattoo places where you can use the touch stick to draw tattoos. The better the tattoo looks, the better criticism you get.
The game view uses a rotatable aerial camera which looks quite similar to the top-down view from the first games, only better. Most of the game is 3D, and for a DS system, it looks amazing. Everything is cell shaded to give the game a cartoon feel.
If you're a GTA fan and DS owner, buy this game now. It has almost everything you could want and expect from a GTA game. Truly one of the best portable GTAs ever.