Was amazing once. It recently underwent a major refactor which removed almost almost all the functionality. The remaining features are often buggy and don't work (e.g. the most important one, disable 60fps videos), or still in development. I will take another look at it in a few years when it's hopefully good again.

Although it definitely does have many useful features, there are far too many bugs for me to justify keeping on using it.
Just to list a few that I've experienced thus far:
• Miniplayer still plays audio even after closing it.
• Switching to any age-restricted video results in a bug that won't allow you to play the video unless you copy/paste the URL into a new tab.
• Videos end for no reason while there's still plenty of time left.
• Autoplay doesn't work half the time, the button doesn't seem to affect whether it autoplays or not.
• Sometimes doesn't switch from the miniplayer even if you're scrolled up at the top of the page.
This being said, I would still recommend trying it out for a bit and seeing if it's glitchy for you.

Simply awesome !

Iridium for YouTube has been seemingly completely wiped. The functionality of it is gone and going into the settings reveals that everything says "coming soon"
wouldn't it make sense to keep the old version working until the new version is done?