Completely breaks web page functionality (i.e. youtube) causing unpredictable behavior.

Used to be 5 stars. Then WebExtension completely hamstrung it. You can't install scripts manually anymore, and some scripts stopped working altogether.

Manipuler Java c'est utile mais dans le même temps greasemonkey accède à une quantité de données personnelles illimitées et ça ce n'est pas acceptable.

If you don't know much about how the internet works, please be careful with this add-on! Here is an interesting blog article about how Greasemonkey scripts can be dangerous for you: https://mobilitydigest.com/dont-use-greasemonkey-scripts/

The documentation is awful. It doesn't work and I don't understand why.

很强了