I for KitKat on my Sprint Note 3 a few days ago. Overall, it seems OK, but only one of the two major problems I had seems to be solved -- the prevention notification thing is supposed to be removed now, but the unstable WiFi issue seems to remain, which is disappointing. Also, the KitKat update seems to have affected how apps can interact with external memory cards, because ES File Explorer is no longer able to copy files between my computer and phone over WiFi. If I use a USB cable to connect them, copying works fine. There are articles on the web that mention how Google (and Samsung, following suit) changed how SD card access works. I'm sure they have their reasons for it, but it seems to be a user-unfriendly change that I for one do not like. It's inconvenient to have to physically connect devices when I used to be able to transfer files and such over WiFi before. I hope a work-around comes out that does not require root access, but for now, IMO the big problems with KitKat on the Note 3 are the unstable WiFi connection (an old, unresolved issue) and the changes to SD card access (new, not sure if it can be fixed or worked around).