While the newly launched Nexus smartphones would ship with the latest Android Marshmallow pre-installed, Google is ready to release the updates to other Nexus smartphones as well.
Google has announced that it would start rolling out the Android 6.0 Marshmallow update for the Nexus 5, Nexus 6, Nexus 7 (2013), Nexus 9 and Nexus Player starting from next week. While the exact date of the release is not yet revealed, sources in the know claim that it is scheduled for October 5. We can also expect the other handset makers to start releasing the updates soon.
The Android Marshmallow offers granular app controls that will let you select permissions manually. It also has native support for fingerprint sensors. Also the Doze battery saving feature uses motion detection to cut off background activity when the phone is in standby to save battery.