In Sims 1 the Servos were just really expensive robot butlers. When they were done cleaning they would go back in their closet until you woke them up again.
But in Sims 2 they became more like other Sims except they didn't eat or sleep but had to recharge in sunlight. They were like a new family member, you could control them like any other Sim, they could talk, look after the kids (if you want to let a weirdo robot do that...), all kinds of stuff. I think they could even have jobs. But when you didn't keep an eye on them they would act really weird sometimes. Like hitting on everybody.
So you either had to keep them busy or make them a Frankenstein's bride. Then you would have two weirdos.
Oh, by the way, PJ, congrats on the promotion!
Ha, thanks. I be watching you all now. O_O