OK, I never looked at the meds they use for the injections but they do work for me. It's pretty sweet when a painful, inflamed pimple that you've been battling for a week with not much progress is gone 10 minutes after the injection.
Yes, the clinic does promote recurring visits. But you can decline. My acne is pretty mild and I lead a pretty busy lifestyle so when I mentioned that I would prefer to not come back once every quarter they simply wrote me repeats for my prescriptions of Benzaclin and vitamin A acid, to last for a year. I don't think the recurring visit is a scam though, I believe once the acne is under control the patient goes on a maintenance plan.
My brother has more severe acne than me and was seeing his family doctor for it for a while, with not much improvement. When he finally took my advice to go to the clinic, it took a few months but he is more clear now than he has been in a long time.