The Cosmetics Cop, Paula Begoun has been dispensing sage advice on skin care products for some time. Though she sells her own products, I do think she is honest about putting great skin care advice out there.
In the past, Paula has been quick to discount the effectiveness of topical retinoids. However, with this recent post, she may be coming around. This article is a good layman's description on the use of retinoids, but she definately left out retinol. Maybe she will come around on this active ingredient soon.