Rated 3 out of 5 stars
After using translator once - out of curiosity rather than necessity - (IIRC, it worked OK.) Upon restart, a webpage was presented entitled: "S3 Google Translator: Advertisement" and which asked for my "support" of the author.
(I did not investigate to see what sort of "support" is sought, but the button to click on to give "support" is green in color. So I presume it asks for "donation$".)
A rather annoying way to ask for payment.
Hi! "S3 Google Translator" is another Add-on, and it is unrelated to this "Google Translator for Firefox" Add-on. I am sorry for their way of annoyance.