The ~950 MB update brings Galaxy S5 users up to speed with the features of Marshmallow, including Doze, Google Now on Tap and app permissions, among others. Since it's the more recent 6.0.1 increment, users can also enjoy additional treats such as the 200+ emoji bundle. For those keen on maintaining a safe, secure device, the August 1 Android security patch is also supplied with this update.
Numbered MMB29M, the single build applies to both the Galaxy S5 and the ruggedized S5 Active. The OTA should be en route through cyberspace if it hasn't reached you already. Indeed, if you don't wish to sit on your hands in wait, fire up the Settings app and navigate to About phone --> Software update --> Check for update.
If you do update your S5 or S5 Active, be sure to let us know how it's running for you by dropping a comment below.