Haven't had the security pop up but I am not going to install Knox anyway.
I did have to reset all of my notifications because they were all silent.
I had a Facebook Pop mp3 in my notifications folder that would play but was coming out silent. Once I replaced it it was fine.
My battery life seems to be improved. I'm at 73% after 12:40 minutes of use and prior to the update I would be somewhere in the 50% to 60% range with the same typical usage. I'll see how long that lasts lol.