Android 6.0 Marshmallow is still awaited on a lot of flagship devices, but Google is never keeping quiet. Google has rolled out first upgrade of 6.0.1 Marshmallow officially.
This New upgrade involves new Unicode 8 Emoi Icons and few tweaks related to table layout and Do Not Disturb Mode.
The Recents button is now to the extreme right, while the Back key is at the left and Home key at the middle. Also, the Do Not Disturb mode gets an until next alarm option again that was available in Android 5.1 Lollipop but was skipped in Android 6.0.
The security update for December has been included in Android 6.0.1 itself. Supported Nexus devices can download the update right now through factory images, while the OTA roll-out will begin soon.
We will soon update the List of Devices with the time frame. Though, The first Devices to update will be Nexus 6P and Nexus 5x.
Adding New emoji Icons require an entire OS update on Android, which is not that great. Google Keyboard can be updated via the Play Store (and needs to be, for the new emoji tabs) the actual fonts are still tied to the system.