Thanks for the nice feedback & your suggestions, so encouraging!

> Can you please enable a couple of sub-task level to make it really useful, similar to Google Task?

We do not plan to add sub tasks at the moment. In general, we do not try to outfeature other task apps out there. We try to be better than email at first, so we have to keep it as simple and natural as possible.

> where does collaborators edit the list?

Everyone who knows the secret URL of a task list can edit it