I would definitely not waste your money on it. The rice they use is no different than any you can buy at a local co-op. It is true for most biologic products too.
A new study done under one of the top waterfowl biologists in the country, Rick Kaminsky, has shown that natural moist soil plant hold over 5x the energy than rice alone. If you are really serious about doing something on your property, I would suggest you do a little research on what natural foods ducks prefer. You can also find his e-mail address on the Mississippi State University web site.
If you aren't as serious about long term, flooded corn field provide cover and is a high energy food that attracts ducks.
"The more habitat on the ground, the more birds in the skies." Ducks Unlimited