|"Supposedly reflects IR" is the key phrase. Perhaps this product works. But I have seen products that purport to reflect IR and they have the IR images to prove it. Problem is the product reflected IR in the midwaveband (3 - 5 micrometers) which for earth temperatures has about 1.1% of total IR radiant energy. It did not reflect well at all at longer wavelengths.
The longwaveband would give 26% of the total radiant energy. Neither tells the entire story. One could have the product measured spectrally over a broad waveband by a company such as Surface Optics Corporation for a nominal price and verify its IR reflectance. See http://www.surfaceoptics.com/Products/Measurements.htm
Knowing the true spectral reflectance of the product would allow a more accurate calculation of expected savings. As radiant loss from the interior of a home to the inside surface of the outside walls often comprises close to 2/3 of the total (not counting infiltration/exfiltration), a product like this that is aesthetically acceptable could be of great value.