It absolutely worked for me. A great grandchild threw up in our bathroom sink, didn't tell us right away, and it created a 100% clog. (Sorry to be so graphic!)
Anyway, I cleaned it out as best I could, and put in one package of Green Gobbler. It took about 15 minutes or so, but suddenly the drain flowed beautifully. I will definitely order it again.
Thanks, Nevadablue, for the heads up about Home Depot.