Rated 5 out of 5 stars

Mark L: "This extension allows Sunbird and Lightning to read and write events to a Google Calendar."
Somehow, I feel, that this implies that either Sunbird or Lightning is required.

Also, I got this to work by following the instructions on the listed homepage. I first tried to your instructions on Google's page, but this resulted to infinite update loop when adding items to calendar (bug perhaps somewhere).

Worked quite well so far (although my testing has been a bit limited)

This review is for a previous version of the add-on (0.6b1).