I have been using this addon at least for a yea, mostly on Chrome.
What I like with this addon is that it will show you cheapest price for the game you are "looking" at on the website you are on so you don''t have to go to seperate website and check for the better price. It wont only work for the games it even works for softwares like Antivirus Softwares.

Why I give this addon 4 stars is that it has some bugs like it can show price for wrong game and then refer the link to wrong game and that could be because there are many games that have similar names out there and therefore the bug.

But this is a addon I would recommend for those who buys a lot of games and don't want to wast to much money and time on searching.