Got my update this morning too! Nice to see Samsung correcting and adjusting issues so soon. I hope they stay on top of things until the device is perfected.
I was having some reboot issues, but havent since updating this morning. Was happening when I turned it on, it would boot up, get to lock screen, and then reboot a second time.
I just got mine yesterday and was surprised when I powered it up that it went through three system updates before I was able to use it. But so far, no stability issues at all. Just a few minutes ago it got pretty laggy while trying to tweet from it, but other than that, it's doing great!