Users of Samsung's venerable Galaxy S III have been on Android 4.1.2 officially for a long time now. That update came out last fall after Google announced Android 4.1 Jelly Bean, and has been the only update available for the most popular phone in Samsung's catalog since then. While many users have been fed up with the seeming lack of support on Samsung's part, it looks like patience may be paying off. Samsung had decided to skip the Android 4.2 update that was planned for the device and move everyone over to Android 4.3 instead, citing a number of reasons including adding support for Samsung's KNOX, a security system that is aimed to enhance the user experience and safety, as well as bring more enterprise customers into the fold. T-Mobile customers saw the official upgrade make its way out in an Over-The-Air update starting yesterday, and now it looks like today will be AT&T's day to start rolling out the update. Users who want to grab it ASAP can head on over to Settings, scroll down to About Device and click Check for Updates. If it tells you there are no updates available yet, never fear, it's just likely not been released in your area. These types of updates are always done on a rolling-type schedule and can be available at any given time. Keep checking periodically in this case.
If you're curious what the update brings, you're in luck. This is easily the biggest update Samsung's ever brought to any of its phones, even including the move from Android 2.3 Gingerbread to Android 4.0 Ice Cream Sandwich for their flagship devices in early 2011. This is because Samsung has been changing their software design little by little, and it's made some fairly huge changes to the way information is organized, especially in places like the system settings, which is now tabbed instead of a huge scrollable list. You'll also notice things like more options in the camera software, automatic pairing via NFC, and of course the inclusion of Samsung KNOX. This isn't the end though, as there's some core UI elements that have been updated, including a general flattening of the OS as we saw when the Galaxy S4 came out in Spring of this year, as well as updated Samsung software like S-Voice.
If you're worried about having problems like the international update has been plagued with, don't be. Remember that the international version of the Galaxy S III is built with Samsung's own Exynos line of processors, whereas the US variants are built around Qualcomm's Snapdragon S4. This means that the software itself has to behave differently, and likely the issues seen on the international models have more to do with the way the software interacts with Samsung's processors than anything else. Users on the XDA-Developers Forum seem to be quite content with the update, whereas international users reported problems immediately. Of course we'll keep you in the loop if anything does end up happening, but know for now that it appears that you will be unable to go back to Android 4.1 if you take the 4.3 update. If you choose to wait it out a few days and see if anything happens, we certainly won't blame you.