This extension rendered FF completely unusable. Had to restore a profile backup.
As soon as I added a site to the block list and saved settings, FF created several hundred new processes, consumed 20GB of memory, freezing itself and the system. Tried to kill the process and then start FF again - same thing happens on start, hundreds of processes, all RAM consumed, etc.
Avoid.

Pointless. Blocks pages, but replaces blocked page with one of it's own. So still getting unwanted pages!!!! Pointless add on.

Stopped working for me after udating.
Please, revert it to the old version

New update seems to have broken a lot of stuff. Blocking Gmail.com now also blocks Google calendar, but only the second page of the weekly view. Why? Super weird. Also when I block a website, I now have to refresh before the block page appears. It just feels very glitchy now, where it was stable and perfect before. Now sure why they pushed out a useless update.

Not only is setting custom rules inordinately difficult, but when I added a new rule, following the documentation, it blocked and overwrote every single tab I had open, (none of which had anything to do with the content of the rule I had written, most of them minimized). Seemingly arbitrarily, this add-on rarely preserves the URL of the site it had just blocked, making it essentially impossible to meaningfully recover anything.
The detour of trying to scan through my history, retracing links and searches to figure out which tabs were for which project and reorganize them is not something that I wanted to do, especially with nothing to show for it.

Can't be used to block only the main page of a specific site without extensive workarounds or knowledge of coding.

Scheduled unblocking no longer works.

I've used the add-on pretty sparingly, so when I tried to add a site today I was frustrated that the block didn't seem to take. It was user error, however. Once I disabled, then re-enabled the add-on, it worked like a charm. Hope I remember this next time...

I love this add-on but the update of 2 days ago seems to have broken some important functionality. When I enter my master password to unblock a site temporarily (such as YouTube, for school or work), I receive "An unexpected error occurred" and I cannot properly unblock any sites. I must disable the extension for the time being. Please update ASAP.

Same as MartinJoster42 this morning, please fix

Worked fine for a long while, properly blocking sites, but now gets stuck in a loop of going back to the blocked screen immediately after the password is entered, even when blocking is paused - making blocked tabs unusable and locked. Have to rate low until this is fixed.

My procrastination is so bad that I just disable this addon in my browser settings. I'm dying.

Good add-on overall. Good for keeping me on task. Only thing is that the quick options menu. I've set it so that there isn't any button to pause blocking, but every time I re-launch Firefox the option to pause blocking shows itself again, and to make it go away, I've got to open the main options menu and click "save options". It's a minor inconvenience, but it can open doors to distraction.

this would be great if the "Schedule Unblocking" option made any goddamn sense.

its working

doesn't work