In fact, Samsung has just started rolling the Android 4.1.2 Jelly Bean update in some countries. Lucky are those folks who already has it first for they are the ones who can tries it out. If you have now yet updated to 4.1.2, surely the update will come soon in your areas, since Samsung releases an update in phases.
Features of Android 4.1.2 Jelly Bean
Here's the new key features on Android 4.1.2 Jelly Bean that is now initially available for the GT-I9300 International version of Galaxy S3, U. S and Canadian variants will be coming on 2013 since it is now already receives the 4.1.1 Jelly bean updates.
Some of the Enhancements in the new update:
-Android 4.1.2 – JZO54K
-Multi-View (Multi-Windows Multitasking, same as in Note II)
-New Gallery App (Same as in Note II)
-Notification Panel (Notification Panel can now be customized)
-Brightness Slider in Notification Panel Can Now Be Disabled
-Smart Rotation (Screen Display adjusts to your angle of sightings)
-Continues Input in Samsung Keyboard (Like Swipe or Android 4.2 Keyboard)
-Paper Artist App
-Group Cast App