This is a very handy add-on that eased some pain in my typing. As I write this review, I am getting an error saying "The add-on was unable to connect with the server. Please try again later."
Good tool, does what it says on the tin within the confines of each language's foibles (i.e. it saves you a lot of time hitting strange key combos but you still need to pay a bit of attention when there are close homographs e.g. tur~tùr which it obviously cannot distinguish)
Useful add-on but it doesn't support all the languages. You should check the list of supported languages before you download it.
[Edited from the initial reply to reflect the change in GeorgHeLL's review]
Thank you for your initial feedback. For the curious, the list of available languages is located at http://accentuate.us/languages
Those that are currently active are highlighted in green, with more being added as often as we receive additional server space. If you would like to help make your language (or any others) active, please consider contributing server space to us by contacting us at firstname.lastname@example.org