With custom notifications, you can send automatic reminders to task or workflow run assignees, or any stakeholders interested in being notified about the workflow run’s progress.
You can schedule the alerts to go out:
Before or after tasks are due
Before or after tasks are completed
When workflow runs are started or completed
You can also add a note along with the reminder emails to make these notifications more personalized.
I have played with this, now. It’s a great add, but I was hoping to customize the resulting Subject line of the sent email. Would be great to see that added at some point if possible.