Very good extension that brings all the good stuff from the Google Chrome counterpart. Yet, I found a bug in the last update. If the option "Show the button to translate the selected text" is disabled, the context menu option to translate selected text won't work. Hoping this helps to bring a fix to it, thank you very much for such a good add-on.
Edit: by the way, I prefer how the icon on the url bar is now displayed, in gray tones rather than the blue icon.