When it works, it's a fantastic add-on to Twitch that provides access to a ton of emotes, customization settings, and tweaks you can use to make your viewing experience better!

With that said, "when it works" is the big caveat. Ever since Mozilla required it to be listed on its Extension store, the app has been going in and out of functionality. Any time Twitch seems to act up, you can directly tie it to FFZ. It could be Twitch updates, Firefox updates, and things outside of the dev's control, but every time it has issues, it really ruins your viewing experience.

Before, it forced the viewing size of the stream to fit onto a 1920x1080 monitor, even though mine is much larger. I couldn't change it without going to fullscreen, which doesn't let you chat. Now, it's resizing the stream to only work with Theater Mode. If you are not viewing the stream in Theater Mode, the volume and play/pause buttons are not visible, a chunk of the stream is not viewable, and all of FFZ's functionality is gone. It took them a couple weeks to fix the first issue, and it may take a similar amount of time for them to fix the current issue. In the meantime, you have to decide whether you want to uninstall FFZ and wait until it's fixed and restore your old settings, or wait until it's fixed and deal with the borked experience in the meantime.

I know the devs are working as hard as they can and you cannot put the blame on them for Twitch/Mozilla doing what they want. I'd still recommend it for the best Twitch viewing experience, but just know it comes with a cost.