In spite of all the warnings I happily updated my S4 and as expected saw very little difference. There was a Knox app now so I thought I would give it a try. Knox creates a secure sandbox for apps. Unlike the Blackberry version, this can be implemented by users without running server side software. It's simple to jump back and forth as you can activate from the notification shade and on the knox home screen there's an icon to return to your home screen. You can view all your unsecured info in the Knox space but not Knox stuff doesn't show up outside of the Knox space. You have the option to delay having to re-enter your password if you are moving back and forth.
All in all I'm pretty impressed with the Knox implementation. It's simple and intuitive and would be great for people who want extra privacy on their device even if it isn't a BYOD.