Both of my now adult daughters used it (19, 24). Neither one had really severe cystic acne, but apparently both are very prone to scarring. I have had guilt about not doing it sooner for my oldest as she does still have some scarring on her cheeks and is a fanatic about skincare and makeup. The younger one did accutane in middle school. She mainly had acne on her back, but the first few times she had any breakouts on her forehead they left some deep scars (that she still has) so I immediately took her to the dermatologist before it became a major problem.
My son has had what I would consider "normal" teenage breakouts and has not had any scarring, so we have not felt any need for him to see a dermatologist.