I'd like for the reader to not waste space on the sides and to zoom in to show only the letters, dark theme. efficient display, good colors and contrast.
Cons: Doesn't recognizes file.epub when dropped on, it used to open them when dropped on any Firefox window, very simplistic I expected a little better color management and to have a library of all opened books previously

nice addon

Very useful application if you're a frequent ebook reader. Great that it comes free of charge and free of advertisements...

Please fix the double quotes becoming single quotes. And I hope you can add an option where it will load the last chapter you read before you closed it without saving it every time using keyboard shortcut "D" aka bookmark. Thank you.

I have changed my review to 5 stars. It seems the problem of files being stored in the Firefox Profile directory has been fixed. The update obviously failed to delete the many unused files in the %mozillaprofile% directory and so I was unaware. I thank the developer for responding so quickly and clearing this matter up. BTW, deleting the \epub directory reduced my profile backup size by about 90%.

OLD REVIEW BELOW, WHICH NO LONGER APPLIES
-----------------------------------------------------------
I have been using this add-on for years. I normally backup my Firefox Profile directory and I have been wondering why it keeps growing in size at an alarming rate. I discovered today that EPubReader stores it's data, including copies of old ePub files I've read and which I no longer need INSIDE the profile folder. This is a huge problem and for this reason I REMOVED this add-on today. Yes, I know the trick of creating a link to another folder, but it's a hassle and not worth it to keep track of so many symbolic or hard links. Any add-on that uses so much space should have a setting to choose the location of its data files.