The Sammy's market Giants, Galaxy S4 and Note 3 are now finally listed to be getting updates of Android Kitkat 4.4. Keeping in mind that the update is only for unlocked Galaxy S4 and Note 3, whereas the phones with the other carrier will get update soon.
Almost everybody knows about the changes that are given in the Kitkat update like better lock screen with full screen music album art support, dedicated camera shortcut and other minor UI enhancements.
The Kitkat update was launched in the months of January and February depending upon the Galaxy line phone and it's carrier. If you haven't received the update yet, you'll soon be notified through their website or by checking manually from your device.