Security | Implemented latest Google Android security fixes |
 Stability | Improvements to memory function as it relates to media applications and ability to prevent need for re-booting when phone is impacted by heavy loading or high temperatures |
 Bluetooth | Enhancement which allows you to launch voice command from bluetooth enabled headset when phone is asleep |
 Wi-Fi | Improvements to Wi-Fi settings to deliver better overall consumer experience as well as  to make it easier to use Mobile Hotspot with your phone |
 Messaging | Improvements to text messaging capability to deliver better user experience |
 Contacts | Improvements are made to maintain all phone book contacts after the OTA upgrade |
You will want to have a descent amount of charge on your device before attempting to update, many suggest over 50%. We like to start off at %100 when ever possible. You will also want to do the downloading via Wi-Fi. We wouldn’t want this to go against your data plan. If you are impatient, like myself, you might be able to prompt the update through Settings > About Phone > System Update. It doesn’t always work, so don’t go tossing your phone across the room if you don’t see it. Good luck and happy updating.
Source: Motorola