I thought you were referring to the company formally known as AuctionAds.com for a minute but then I realised they are nowcalled ShoppingAds.com. Shopping.com is a price comparison site isn't it? I think you could earn more with PTC sites like AdsDAQ, Adsense, etc.
I have joined that site. They said that You will earn $5 for 5 reviews. But i have made it but they don't pay me until right now. Many products that you must write for review.