I checked them out at Target, but didn't buy them. They smelled nice, but seem like an unneeded item for me. They make no softening claims, unlike the Purex Crystals, which do soften but don't control static.
I don't understand the marketing strategy. If someone likes scented laundry, wouldn't they buy scented detergent and/or softeners already? Since the scents of the unstoppables don't match existing Tide or Downy scents, it is not to boost an existing scent. It seems one would need to use unscented products, then add this so as to not mix scents... but I thought most people who bought the unscented products do so because they don't want scents, due to allergies or other reasons.
I guess the most logical reason to get it would be if someone in your family liked scented laundry, and another requires the unscented stuff, then you can buy one detergent and just add scent when desired. Or maybe so people can be their own scent alchemists. Tide Clean Breeze detergent, Downy Orchid Allure softener, with Downy Unstopables Lush in-wash scent booster: I am getting a little scared!