I love to try new products like this, but I think it will last just about as long as the Oxi Detergent Ball did. Remember that one? I used them on lightly-soiled loads in my front-loader, because there was no suds. But they weren't up to tackling greasy stains..or stains in general.
I printed the $1-off coupon and will head out to my local HyVee grocery store tomorrow.
As has been mentioned, these would be great to take on vacation or when staying in hotels with coin-op laundry facilities. I stay at Candlewood Suites in Minneapolis, where the laundry (GE machines) is free, so I always make sure to do at least one load.