When a To-Do is assigned to a person or persons, the notification settings can be set to allow that person to get an email. That's good. There does not seem to be a way to control the settings so that only the team members associated with a To-Do are notified. This is imperative so as to allow person to person communication through To-Dos to resolve issues. (i.e. I want to be notified if someone comments on a To-Do I created or was assigned to, but not for comments on To-Dos I am not involved with.)
Thanks for your feedback. We are working on this concern and we will keep you posted on the support case we have created for you. Please feel free to reach out to us if you have any other feedback.