The rollout should start in a few weeks’ time as Samsung has committed to bring Android 4.3 Jelly bean to its Galaxy SIII former flagship. If around flashing a ROM manually, you know your way, as a pre-release version of the Android 4.3 build has just surfaced, you don’t even have to wait that long.
Although the beta version may have a bug or two, but it is reportedly stable enough to work as a daily driver. Including the transparent notification bar and a new settings menu with tabbed interface as found on more recent Samsung flagship, it brings a number of UI changes.
Unfortunately, still the majority of the widgets in this build are using the old design and enabling of Samsung Knox is not done. In order to not worry about missing on the security feature, this should change in the final Android 4.3 ROM for the galaxy SIII.