Rated 5 out of 5 stars

Great!!!! Thank you! I've been waiting for this since the Remember The Milk Provider add-on stopped working with TBird updates (after 3.0.11). However, after using it for a couple of days, I started getting "Modification Failed" errors when adding new tasks. Interestingly, marking tasks 'complete' still syncs with the RTM server fine. Any troubleshooting ideas would be greatly appreciated!

UPDATE: In thunderbird/Storm Cows, I deleted the RTM list "All Tasks" and added the list "Inbox" instead and now everything is working perfectly! Thanks again, great app!!

This review is for a previous version of the add-on (0.3). 

Glad you got it working! If you add a calendar associated with an RTM Smart List, you'll get that error if you try to add new tasks to it. I've logged an issue for this and I'm hoping to get it fixed up in the future:

https://github.com/moldybeats/stormcows/issues/3