I'm unsure if this actually worked, or if I was one of the lucky ones. I'm average tech-wise, but took my time and read a lot of forums prior to installing KitKat.
Here's what I did, very simply. Hope it works for you too:
1. Deleted any unused / unwanted apps. Installed any updates available for the keepers.
2. Moved any apps stored on the SD card over to device memory. (I did this since the KitKat doesn't write files to SD card - figured this may make the new OS install with less glitches).
3. Installed and ran Clean Master (Clean Master - Free Optimizer - Android Apps on Google Play). This freed up over 5GB of space on the S3 device memory!
4. Ran KitKat installation.
5. Held breath.
6. Messed with a few settings and charged overnight.
So far for the past 5 hours this morning I have experienced no issues, and seemingly better battery life.
Thanks for this info. Did you upgrade to KitKat from JellyBean or an earlier version? My S3 got the JellyBean update in December and my device has been terrible ever since. Battery life plummeted, numerous wifi and settings issues surfaced, among other things. VZW Customer Service has been basically useless, both here on the forum and on Twitter. I'm hesitant to upgrade to KitKat if it doesn't fix what JellyBean broke or breaks something else.
Thanks in advance.
I upgraded from Jelly Bean. I think when I installed Ice Cream Sandwich on my S2 I had major issues which forced a factory reset.
Going on 3 days with excellent battery life and no glitches or issues with S3/KitKat.