Simply does not work.

they must have fixed it cause it works now.
it's case sensitive so you have to type the subreddit name exactly, you don't need the r/ part, and also takes a second to load.

you will see a subreddit you thought you blocked but give it a second and it goes away.
it's good but it needs a button next to the subreddit name to block it. i would give it 5 stars if that feature was there.

Just straight up does not work. Stopped working a few weeks ago and the lack of updates had me just delete it

There's not a lot of details on this addon and how it works, so it's hard to say if its working as intended, but for me it does not work well. I use the "new" design, and the addon doesn't do much there, so not sure if it was meant for the "old" design. I very occasionally see a post for a blocked sub disappear because of the addon, but very rarely, and most of the time it does nothing (meaning I see tons of posts from blocked subs while viewing r/all). There are a few other minor nitpicks, like it doesn't prevent you from adding duplicates to the block list. But overall, it's just not effective.