Useless. Doesn't actually show price. If it does, it is not easily accessible. It's trying to promote other functions like recommending other products to buy instead of what it is named as.

Avoid this kind of extensions that can collect what you are looking on the internet, it's just collecting informations on you to profile you and similar customers to target ads/products/services. That's desguished spyware in counterpart to provide you a pretended nice service.

And just about the service provided: this kind of extensions (lots of similar exist like this one) can modify the webpages on-the-fly and also can censure some parts or search results to guide you to buy to a specific seller instead of a concurrent. And guess who is paying the extension editor to do that?

Mind again before addin browser extensions!