I like the tracking and how I get the best price. The add-on causes Firefox to run slow, lock up, crash, and run so slow that Firefox is unusable. This was on 5 different computers running Linux Mint, Debian, Kali, Tails, Windows 7 and Windows 10. Tested and when I removed it Firefox problems were instantly solved. I do not recommend this add on however at a later time if these bugs are fixed then I would recommend it. I would have rated it a 0 however that is not 1 of the choices.