A few days ago, we got word that Verizon's KitKat update to the Samsung Galaxy S4 was scheduled for release on May 2nd, 2014. However, this morning the OTA update was popping up on devices all over the states, ready for download and installation.
Galaxy S4 owners on various other carriers have reported a myriad of problems with the new update, such as increased battery drain, missing apps, and the inability to write to their SD cards—most of which we've been able to find workarounds for. Presumably, the reason Verizon waited so long to issue their update was to iron out fixes for most of these issues.
Head over to Settings -> More -> About device -> Software update to check if the OTA has made its way over to your device.