Directions on how to install Android 4.3 on the device can be found at the sourcelink. The version of Android leaked is JWR66V following up on the existing leak which is JWR66N. The update includes improvements to the battery (always a good thing), and you can now wirelessly charge the phone with the power off. Non-rooted units can now use Google Wallet. There are some bugs associated with this leaked build including difficulties with CNN and HBO Go.
Google is expected to unveil Android 4.3 at the same July 24th event that will introduce the new Google Nexus 7 tablet that should be powered by Android 4.3 out of the box. Since the update doesn't require testing by a carrier, it shouldn't be too long after the announcement that Android 4.3 is ready to be downloaded on the Google Play edition of the Samsung Galaxy S4.
source: XDADevelopers via AndroidAuthority