What is Quick Add
The settings menu shows an option for Quick Add to be on or off. I can't find anywhere that describes what that is.
When "Quick add" is checked, a TD icon at the top left of your android status bar will show up. If you pull down the notification bar, you will see "Add Task" button, which pops up a dialog to add a new task.
It's the quickest way to add a new task when needed :)