I don't know anything about the DS version but I really didn't like the game on the Wii. I thought it was gonna be awesome and I really love the art style and the amount of character customisation BUT....
There were some major problems with loading. There's a loading screen every 5 minutes if you're moving around a lot. A loading screen to move to a new area, a loading screen every time you go into a building, a loading screen every time you leave a building and even after the loading is finished things are still jerky and not very smooth at all... it kinda ruined the game for me and it made me not wanna play beyond getting a 5-star town. :\
There's not enough character interaction... sure you can do some pretty fun actions now and then but it's not very in-depth. The only thing really good about the game is making your own stuff... you can make anything... but again, it's ruined by how much the flow of the game is disrupted. :S
Of course, if that isn't gonna bother you then buy it. Animal Crossing is much better in my opinion.