Tries to imitate life, but only partially succeeds.
Sims, as they are called, are little 'people' that speak possibly the most hilarious language I've ever heard. They have needs and jobs, and you'll end up spending most of your time either increasing their skills, socialising with friends, or spending very long amounts of time looking at your little sims in the bathroom (for some reason, it takes sims an hour to relieve themselves).
The fact that the sim-day isn't very long, and to keep your sims needs up you need to be playing close attention to them (their AI is similar to that of other games of 2000: a little buggy), or they'll end up combusting by setting the stove alight.
The main bone I have to pick at The Sims is that the enjoyment stops at the house. Why can't they go to the movies? Why can't you follow them to work? Why can't you go to your friends houses, when they can come to you? I'm sure that the answers are of the technical capacity area, but there's only so much you can do in the house, and it gets boring if you're not intending on playing it casually.