Why? WHY? WHYYYYYYYY!?!
You can play FREE PLAY mode or STORY mode, both with one or two people, though these modes are basically the same, except, in Story mode, you can only make enough characters for the one or two players, no more, which really takes away the family part. In story, you basically go from house to house, mooching off of strangers by moving into their homes without permission. You go, completing ambitions, like in the PC version, but it's just annoying, as you can't play as babies or kids, so their is no variety to the ambitions you must complete. But, you have to do these to unlock new items, but really, there is not enough stuff, as they took all the fun stuff from the PC version out of this version. You can mix and match all your clothes, but this is boring, and after a while, you would've done every combination there is. A new thing, is controlling the character with the thumbstick, which is annoying, but the original version is so slow, you'll have to live through the horror of the thumbstick. Also, your character doesn't always do what you want. This isn't like when they're depressed, and won't work. This is just unresponsive, and you may have to try up to around six times to get it to work. The convesations are weird, you can't simply do one thing then stop, the whole world goes blurry except the people talking, and you have to get the relationships perfect, or it goes down the pooper.
The only good thing is the graphics. The sound is frustrating, as if you can't find the radio, the music won't stop. Also, the simmish talk or whatever doesn't stop, and it gets really annoying.
Overall, The Sims 2 is nowhere near as good as the PC version, and if you don't wanna get it on the PC, get it on the DS.