The BOD was noticed by many iPhone 5S users worldwide and its cause seems to be something related to how iOS7 works with the new hardware of the iPhone 5S. Furthermore, there have been reports that apps are crashing close to as twice more often on the iPhone 5S compared with iPhone 5 and iPhone 5C.
The most common action that generates the BOD on iPhone 5S is when a user tries to access multiple iWork applications. Some people already compare the BOD seen on the iPhone with the Unwanted Windows "Feature" seen in old personal computers running Windows.
Apple usually releases update fixes very quickly but for this one it still remains to be seen how the company will address the issue.