to be added to the Samsung Galaxy S III is Smart Rotation. Using the phone's front-facing camera, the device figures out the orientation of your face and adjusts the screen accordingly. This feature is off by default on the Samsung GALAXY Note II. Another feature coming to the Samsung Galaxy S III is Paper Artist which allows you to stylize an image using a number of options. Without the S Pen, you will have to use your finger to use the feature. A new Gallery application is part of the update along with a virtual QWERTY similar to Swype.
The leaked update is for the international version of the Samsung Galaxy S III, although there is no reason not to expect these features on the U.S. carrier versions of the phone. The update is expected next month and there is some speculation that the original Samsung GALAXY Note will also be getting many of the new features on its successor.
In the meantime, the ROM containing Android 4.1.2 for the GT-i9300 can be found at the sourcelink and there are the usual warnings. Think brick. The ROM is a pre-rooted testing build, spliced together from a system dump and is not signed by Samsung. You could always wait for the official release.
source: SamMobile via AndroidCentral