The latest and greatest Android 4.3 update for Samsung Galaxy S4, S3 and Note 2 is not so far now.
In the Samsung Unpacked event at IFA 2013, Samsung has said that the Android 4.3 update will be hitting the galaxy S4 and S3 devices in October. Though the Note 2 was not specifically mentioned by Samsung, it should be there in the list as it is a newer device than S3 and has not got an update since last year and is still on Android 4.1.
Changes in Android 4.3 for Samsung Galaxy S4, S3 and Note 2
If the newly released Galaxy Note 3 is any sign, we may not be seeing any significant interface changes in the Android 4.3 update.
It will rather bring the feature updates such as OpenGL ES 3.0 support, Bluetooth 4.0 support etc. The Bluetooth 4.0 support will also makes these devices compatible with the newly released Galaxy Gear smartwatch.
For the Note 2, the update might bring the new S-Pen features that were released with the Note 3. We still have to wait for an official confirmation from Samsung for that.