Now available over-the-air (OTA), the update is 684MB in size and brings the usual KitKat goodies. To manually look for the update, go Settings > About phone > Software update. You can also check for the update via LG update tool on your PC.
The official change-log is not available but G Pro owners can expect to see immersive mode, cloud-print support, user-interface improvements, updated Hangouts app, new downloads app, restyled status and navigation bars, stronger security, and battery life improvements.
If you have already updated your phone to KitKat, do let us know about the experience in comments.
In related news, LG Brazil has stated that the KitKat update for Optimus G smartphone will be arriving in August-end, which is about two months away.
Thanks Monish for the tip