Fortunately, a source on Reddit did provide us with an unofficial changelog:
- General reliability improvements
- Battery and performance improvements
- Typing on Polish keyboard in Outlook Mail
- Turn by turn directions over Bluetooth in car
- Battery usage with Iris Recognition
- Reliability of quick actions settings page
- MS Band use with Cortana
To download, scroll down to settings, search for "Phone Update" and search for an update now.
Did you notice any new changes? Please do mention them in comments section below.