The extension does what it is meant to do. It increases the volume on all sites I have tried it on. This is especially useful when videos are uploaded with a low volume.
The only minor thing I dislike is the frequent display of tips and requests to insert advertisements into other pages.

simple and easy to use

Compre oque promete

works really nice!

does what it says, does it well.

Works perfectly, but breaks video playback on certain sites.

Awesome

work's perfectly!

Brilliant.

Boosts volume