From what I can tell,
The Urbz: Sims in the City for the Nintendo DS is almost a direct port of its GBA counterpart. The only major difference is that
Griptonite Games has moved the PDA (the menu system) off onto the touch screen.
You start the game off as a janitor for the King Tower, but when Daddy Bigbucks buys the place and Mr. King disappears, you have to find a new place to hang your hat. Throughout the rest of the game, you work your way through the various parts of Miniopolis and attempt to run Bigbucks out of town. The Urbz is broken into five missions that starts off at the tower, goes to the urban life, then the waterfront, the bayou, and finally the downtown area where you get to go up against the big man himself.
There is also a sixth mission that involves finding plans to a secret island where you get to create your own pets in a fashion not quite entirely unlike Jurassic Park.
Just like in the other Sims games, you’ll have to monitor your character’s moods. As you run around the city, you’ll have to feed, bathe, entertain, and rest your Urb. You also need to earn Simoleons (Sim currency) by playing mini games (jobs). These jobs consist of Squeegee Clean, Doctor Max Stat!, Moogoo Monkey, Amber Extraction, RNA Splicing, Street Artist, as well as five or six other mini games. Once you have unlocked a game, you can go to it at any point.
One of the major aspects of Sims in the City is your rep and where you stand in your Rep Group. There are several reps groups including nerdies and streeties. Where you start off is based on how you answered some questions at the beginning of the game. You climb your way through the ranks of the groups by talking to and impressing various people. You will also earn beads called Xizzles. Since a lot of the game demands that you have a good rep -- you need to work hard at pleasing other urbz in order to progress.