Rated 3 out of 5 stars

Sync works nicely. The advantage over Provider for Google Calendar with Lightning is that you can select multiple task lists.

However, there are a number of limitations:
* it appears only to sync one Google account (I need several)
* it initially chose to live in the Folder Pane, and didn't sync (errors in the Error Log) - when I changed the addon's option to put itself in the Today Pane and restarted, it asked me to choose an account, did the OAuth authentication, and worked fine from there
* can't add or delete task lists - but this isn't a big deal really
* can't reorder tasks and although it shows subtasks, I can't figure out how to indent or outdent them