Most people here have. Check the last few pages of this forum and you'll see lots of conversations on it. For the most part, it's OK, maybe even worth a try. But it doesn't work for everyone. I've used it for a couple of years. I like how soft it makes my skin, but don't like how it bleaches my pillow cases. I also really like the sulfer mask they make.
Several people here have been talking about the asprin mask. I gave it a shot, and I have to say, I like it way better, both for the price and the effect. But there's no obligation to stay with proactive if you don't like it. So there's really no harm in trying it out.