It seems like a no-brainer for deletes. I don't need to delete the child (or grand-child) tables because the stored proc called by the delete on the parent had to delete the child data in order to delete the parent.
However, I tried using it with the unintended side effect that if I do modify rows in the parent AND child tables, updating the rows on the parent accept changes on the child before it has been updated. So the child table never gets updated because the changes are accepted.
I cannot think of a reason to use this feature for updates/adds. Anyone?