I did it for a while. I think to get the most out of it you really have to buy into the whole system. You essentially collect coupons for 6 weeks and then she tells you when the best time is to use them. Overall, I wasn't really wowed that I was getting better deals from the system than just reading the circulars and buying stuff on sale. I also think it works best if you eat a lot of packaged foods, e.g. combine a sale and a coupon for cake mix or spaghetti sauce and get a good deal. Not so much for fresh produce, meat and other items you rarely see coupons for. You can usually try it for a month because it's free or nearly free.
When I did it, Safeway was the only local store for me that was on there and we don't shop there anymore. I'm not sure if she's added others.
You can also try
Grocery Coupons, Coupons, Free Samples, Online Coupons, Restaurant Coupons. It's free.