
According to AndroidSaS‘ source, the Android 4.3 update will mainly be a security and bug fix update, and that it doesn't have any new features from the Galaxy S4. There's still time before the final update hits though, so we'll just have to wait it out for more details (and a leaked firmware) to see what the update really brings to Samsung's yesteryear flagship.
Update: On closer inspection, the image does seem to be fake, so don't take it too seriously. Android 4.3 is surely coming though.