It's fine.

There are a little too many options for my taste but that's a nitpick.

The real problem though is its supposed auto stop feature. It almost never works when you load a video in the foreground. Then, because it doesn't load the entire thing, it plays a second or so of the video in 240p or something, then stops, starts forward in the preferred resolution and then stops.
It always works with background tabs though.

But the auto play feature needs to be tightened up.

Essa extensão é indispensável à todos os usuários que passam boa parte do seu tempo no YouTube!

Does the job pretty well. Loads of customizational options available and even with constant improvements in YouTube's Advertisement codes, the extension manages to skip ads for you for free. Must need for anyone who watches a lot of YouTube.

Great experience for youtube.

Simplismente indispensável! Pense em tudo que incomoda no YouTube... este add-on é a solução.

It broke the comment section for me; it doesn't appear anymore, even after I removed the extension.