The extension is quite useful, moreover it allows you to actually download a page in PDF

Customizable reader mode, 'nuff said.
Basically what Firefox used to have before they removed it.

Needed this for Reddit, it didn't work. (Only shows description in reader view and shows no posts.) Might work for other things.

It's a definite improvement on Firefox's own reader view, and very customizable.

I have some vision problems and this add-on really helps.

I also use this to quickly convert articles into pretty looking documents that I can print, or save as PDF for my e-reader.

Wonderful options visually, but the text-to-speech is currently broken, at least for me.

I was trying to skip ahead to later in a page and it would only play from the beginning. Even waiting it out didn't help because it would read the first few paragraphs and then stop.

Best tool for reading view

This is the best readability add-on for Firefox at the moment - it's reliable (doesn't remove the full article LOL, like for instance the Clearly Reader add-on does), its editor funcitonality is top-notch, and the default reader layout is just beautiful and calming.