First thing to install in TB Rated 5 out of 5 stars

Great extension, really adds useful functionality to TB.The guys at the Mozilla Calendar Project also do a fine job to stay in line with the constantly changing code at the Google-Calendar end, in collaboration with the 'ṕrovider for Google Calendar' add-on.
In case something seems to stop working, they usually have a solution ready at their blog (https://blog.mozilla.org/calendar/)

This review is for a previous version of the add-on (1.9.1).