This add-on is a beauty. 100%. It's interface is incredibly user friendly. And it's packed with every feature you could possibly think of for creating and working with screenshots. I am able to quickly cut, edit, and copy/paste the image to another browser window directly from the app without needing to save it to my hard disk.
It is stable. Enjoys stable updates regularly and doesn't create issues with the browser or the pages I am viewing. Can't say enough about it!