It seems that Samsung has put its software development department in high gear as we are hearing that early builds of Android KitKat for the Galaxy S4 (GT-I9505, Snapdragon 600) and Note 3 (SM-N9005) are available online. The new updates have not been officially announced by Samsung, which means the updates are only test builds and could have some minor bugs.
According to Sam Mobile, the new update brings in some new tweaks to the UI, like new and updated white status bar icons instead of the old coloured ones. The toggles in the notification drop down menu however, don’t share the new look and have the same old green colour. There is also an addition of a camera icon on the lower right corner of the lock screen. Sam Mobile has also confirmed that there has been improvement in performance and even the benchmark results are better than the ones done before the update.
If you cannot wait for the official release, then you can grab the firmware and flash it yourself. However if you are new to flashing, then we would suggest you to wait for the official release as you can end up damaging your smartphone’s software.
Source: Sam Mobile (Galaxy S4), Sam Mobile (Galaxy Note 3)