AT&T's Samsung Galaxy S4 joins the update party
According to those AT&T customers who have downloaded and installed the update, it seems to bring smoother animation and faster performance to the phone. As usual with a software update delivered OTA, it is sent out in phases which means not everyone will receive it on the same day. You can try to see if your device has received the update by going to Settings > More > About device > Software update. If that fails to do the trick, you can hook your Samsung Galaxy S4 up to your PC and pull the new software version out of Samsung Kies.