What every best has:
The only non-user review we found was from a Washington affiliate station, KEPR, as part of their "Will It Work?" series. In the video, staffers bring out a sagging sofa for the experiment, only to read in the Furniture Fix instructions that at least three sets are required for a sofa. Fortunately, they find a matching sagging loveseat, and after sliding several Furniture Fix panels underneath the cushions they find that the cushion has actually been lifted by two inches. While the results are successful, they conclude that the Furniture Fix doesn't make the loveseat any more comfortable -- and add that you can probably get the same results by sliding a TV tray under the cushions.
Another hiccup is the product's website; customers report overcharging, order doubling, aggressive telemarketing and the impossibility of getting a refund. According to customers, not only is there no order confirmation page on the Furniture Fix website, but the navigation is extremely (some say deliberately) confusing; they say that clicking the button for a free set will actually double or triple a paid order, adding additional shipping and handling charges. Calling customer service to cancel the order does no good; callers are told to call back in a few hours and, when they do, are told that it's too late to cancel because the order has already been shipped.
In the end, Furniture Fix might help bolster sagging cushions in smaller items, but you can probably make your own solution with a piece of plastic or light plywood.