This is the first KitKat update for US carriers on the Galaxy S4, showcasing Sprint's recent push to give their customers the latest and greatest well before their competitors.
If you haven't yet received a notification to update, try forcing and OTA (over the air) update by going to Settings -> More -> About device -> Software update -> Check for updates.
Did you get your update? Let us know what new stuff you found in the comments below.
Have an iPhone? See everything that's new with Apple's latest iOS update: