I hate this update. I hope they push out a new one soon. Since the update, I have several issues. The biggest issue is that the screen is not as responsive and the phone seems to lag. Sometimes I have to swipe my finger across the screen 2 or 3 times before it does anything. When I play games, sometimes it doesn't even register that I touched the screen. Sometimes I tap in one place, only to have something happen elsewhere. It thinks I touched somewhere else. You get the picture.
Another issue is that I can no longer swipe from left to right on a contact to call them. I can swipe right to left and it will text them, but the other way rarely works. Sometimes I can swipe 10-20 times and it may work. This may have something to do with the screen issues I mentioned.
The Multi-Window feature is useless on a phone. I like it on the tablet, but there is no reason to have it on a phone.
If AT&T has not forced the update on you yet, don't get it. At some point you will have no choice though. My wife's phone prompted her to update and she said no several times. It eventually updated without giving her a choice.