I updated last night. I have a US 16gb Wifi only Tab 7 plus. Also have a 16gb Micro SD installed. It was rooted. I just ran the upgrade without uninstalling root. Upgrade took about 25 minutes, auto rebooting twice. No problems.
Results - All my appliications and setting remained intact. Root is still there (verified by RootChecker). The tablet seems to scroll between home screens more smoothly. Also animations going from app drawer to homescreen appear very smooth.
I previously had SOD very often and had to install AutoAirplaneMode app to fix it. After upgrade a tried not using -AutoAirplaneMode. So far no SODs after numerous screen off and on and sleep/wake. Of course SODs were random before but so far this upgrade looks very promising - no downsides, faster screen operations and improved stability.
I recommend it but YMMV