By googling on the build number I did find the AT&T official release notice for this update, but it doesn't really say what it fixes. I tried to paste the URL for it here, but the forum won't let me because I don't have enough posts.
But this is all it says:
Update summary
AT&T released a new software update for the Samsung Galaxy S III (SGH-i747) via Firmware Over the Air (FOTA) over Wi-Fi on November 12, 2014.
Software Update Includes
- Android OS Enhancements
On the xda-developers forum, someone said "It just looks like more bloat and a patched kernel so towelroot will no longer work. It might even lock the bootloader." and someone else said "I'm afraid it does soft brick a rooted phone."
Fortunately I'm not rooted, so I don't have to worry. Though I sure wish I could get rid of the damned AT&T block on sharing wifi hotspot. Even out of the country on a different sim card, I can't use the hotspot on my phone because that darned bit of software. Have been considering rooting, but am timid. This is why, I guess.