Rated 3 out of 5 stars

Excellent! But broken with Ubuntu 15.10 - no Events show in Calendar Panel.

This review is for a previous version of the add-on (0.4.1). 

Thanks for the input.
Issue has been fixed in version 0.4.2.
It takes some time for Mozilla to evaluate the addon.
Feel free to download it for Support Site - it is a Bitbucket space where you can raise issues or download the addon.