My DD had occastional breakouts and wanted to try Proactive to prevent them. She used it for about a year with fairly good results. Then, all of a sudden, she developed dry, red, itchy, painful patches on her face. She called the Proactive company and asked if they had anything more gentle, since Proactive seemed to be too strong for her. They told her she should be careful to use all the steps of the program every time (their assessment was apparently that she was not moisturizing enough).
She continued to use it for a while, but her face hurt too much to keep using it. She had actually developed a sensitivity to the active ingredient. When she called to discontinue her automatic program, they gave her kind of a hard time about and told her to just decrease the frequency of using the product. When she said she had already done that and her skin was no better, they tried to talk us into using their new product for sensitive skin (now they had one).
Anyway, she feels that Proactive ruined her skin. She went from occasional mild breakouts before trying it to having breakouts all the time - and being extremely sensitive to most of the available products after using it.
I would not recommend it to anyone, and if you do choose to use it, stop right away at the first signs of any problems.