This extension does exactly what it says. It does it well and without any negative effect on my browsing. It's not malware (scanned it, lol), and Mozilla is not harming its users.

Gee, I wonder why there are so many 1 star reviews with no specifics or logic behind the ratings.

I'm sure it's nothing to do with the fact that this extension exposes fake reviews of for-profit sellers' products on giant for-profit web sites.

Yeah, sure. A highly respected, non-profit company (Mozilla) that exists entirely to protect users' privacy and provide a high-quality, safer (than Chrome, e.g.) online experience, is for some mysterious reason harvesting private data to harm their users. It makes perfect sense if you don't think about it.