As for what to expect from the update, of course you'll get all of Marshmallow's improvements, including Doze, Now on Tap, and granular app permissions. Verizon also says that the update brings along the "latest security patches."
The update is only just started rolling out, so it may take some time to appear for you. However, you can always try checking for an update manually by going to Settings, About phone, and checking for the update. After you've downloaded the update, be sure to hit up our forums to discuss the changes.