'Potentially' the best add-on since Ublock Origin.
Now I can read pages in English, as opposed to the Universal State of Ambiguity that's rapidly replacing it!

Unfortunately, it's messing-up script-related (js) content.
Eg, Changing text/formatting colours, preventing js-related images, videos, etc. from rendering.

Finding more wrong with it as time goes by. It's becoming more annoying than the cause of the problems I installed it to remedy.

We could also do with the option to exclude specific domains.

Some clear and concise usage instruction would also be a welcomed addition.

Once the developer has finished the plug-in and fixed all the outstanding faults, I will compile a downloadable list to enable automatic US-American to English translation.

Due to the above issues, I have downgraded it to 3 until further improvements are made.
:-(

Although that I this is a very interesting extension and can be a time saver to many text writing users on the web, I gave only 3 stars because it can ONLY replace text and symbols in the text box of "Google translate" website only. It doesn't work on any other website, or Addon/extension which have full/or pop up text page input window. Also it takes two steps to do this job, whereas other similar Addons do this with one-click of the button. (here you must click the addon on the toolbar, click Replace from the list, and after a Sidebar will open on the right side of the window... which is too much of actions to do).
-> For now I will go with the two similar addons which are very convenient to me. Those are: ◾ Replace by erosman and the ◾ Find & Replace for Text Editing by Dalimil Hajek.
Fix this problem (to be able to replace text everywhere and make the process in only one step), and I will give 5 stars on my rating.

Very well to correct people's misspellings.
I would like the extension to correct the text on some url only.

Good for simple texts. I missed the possibility to save/view replace history and to replace large content in text areas like youtube description videos.

You must add at least one substitution and correct all errors
Все видимые поля я заполнил, что ей ещё нужно?

И ещё, хорошо бы менять только открытый для редактирования текст, а не отображаемый текст.
И эта версия почему-т не русифицированная, прежняя была лучше.

...it doesn't work with embedded Twitter tweets. At all. Even doing the manual "replace with substitution list" does absolutely nothing. I think this used to work, but not anymore.