The full changelog — which comes courtesy of Google — can be seen below:
Android 6.0.1 (Marshmallow)
Exercise greater control over app permissions
Experience enhanced battery-life through Doze
Redesigned App Drawer
If you’re a US Cellular customer, own a Galaxy Note 4 and would like to see if the Marshmallow update is ready for your handset, simply head into Settings > About Device > Software Update > Update Now. Alternatively, you could always wait until you receive a push notification prompting you to install the upgrade.