Impossible to know if this product works without doing scientific tests. However my gas safe engineer was happy to install it as directed but he had never heard of the product. No clear instructions on bottle of how to dispose of it. However I would recommend it because if it does work it will reduce the amount of gas consumed by boiler, by up-to 15%.
I have now had product installed for a few years and have noticed my gas consumption appears to have gone down and two gas engineers have commented how clean the burners boiler were even after 2 years of use. I can definitely recommend this product which is now much cheaper than when I bought it.
Energy Trust recommended so can't really add anymore to a recommendation like that apart from should pay for its self with it's first year and carry on saving, so should go some way to help pay for the yearly service!