I've been interested in KeraStraight after I saw the ad in the ulta circular, and I did manage to find some reviews on it. (by the way, I'm 3b/3c too!!) It originated in the UK, and that is where almost all of the reviews are from, but the reviews were pretty darn good. About 80% raved over the treatment, especially compared to BKT, etc. 15% said it only lasted anywhere from 1-3 months as opposed to the advertised 14 weeks. 5% said that as soon as they washed it out their hair returned to normal, but hey, no product is perfect.
Everyone seemed to agree that the 1st time it isn't as effective as say, the 2nd or 3rd time, but I think that goes for any treatment.
Hope I helped!