The update was pushed out by Samsung recently to fix the Exynos vulnerability and reset code bugs as well as to correct the "Sudden Death" issue that is plaguing Samsung Galaxy S IIIs.
The Exynos Vulnerability is a bug where a security flaw in Exynos 4210 and 4412 devices allows for the device to be taken over remotely with root access to device memory at the hardware level.
Most of us by now have heard of the reset code bug, where a malicious website link could be sent to the device via most any means and when the malicious link is clicked a single line of code on the site would send the device into a factory reset with no way to cancel the process. This is done by triggering factory reset through USSD code.
The third issue fixed in this update is actually much more common on Galaxy S III devices, but that could only be because that device has been around much longer and most users that have experience the "sudden death" of their device have been about six months or so into the devices life.
But the battery suffers
Most expect that after updating their devices, for the device to be all-around better, hence-updated. That is not necessarily the case with this most recent evolution of the N7100's firmware. Although some major bugs are fixed, many user's of the device are complaining of losses of up to 12 hours of stand-by time and 1-2 hrs off of their normal active use times.
Even so, this is a problem with this particular update, it is not commonplace for Samsung to introduce performance issues into a firmware and we must expect them to push out another version of the firmware to fix this latest battery issue before the much-anticipated release of the Android 4.2.1/4.2.2 update for the Note II.
Through reading comments about the issue, it can be deduced that this issue is affecting a majority of users of the N7100. Most users though, are only reporting a reduced battery life of between 5%-15%. It seems that the consensus is, if you get the update pushed to you device, you should take it. It is much better to have a bit poorer battery life than to have someone maliciously take over the root of your device, to have someone maliciously reset your device, or possibly worst of all have your device go off never to return again.