Rated 2 out of 5 stars

Doesn't work with two-factor authentication. Google complains that cookies are not supported and doesn't allow you to log in.

This review is for a previous version of the add-on (2.0.5). 

Please try to do some research before posting a review and claiming something doesn't work. gContactSync supports two-factor authentication...the problem is that you have Thunderbird configured to block cookies.

See http://www.pirules.org/addons/gcontactsync/faq.php#cookies or http://pirules.org/forum/index.php?topic=619.0