I have had my Note 3 since Christmas and it has been fine with no physical damage or anything since I have always had an otterbox on it. I update to KitKat this previous saturday and it falls apart. It does not receive notifications anymore. It does not receive text messages unless I turn it off/on again. It is stuck in an endless "sending" animation and I am never informed if it sends the message or not. It is very slow and laggy. The battery life is about 4 hours now if I am lucky and that is without using it. I have cleared its cache, put it in safe mode, removed and reinserted the battery. I have tried everything I could think of and have lost my patience. Every day it seems to get a new problem. I wish I had just gotten an iPhone originally. What is recommended that I do?
You may have to do a factory reset. Be sure to back up any files you want to keep before doing so. I was fortunate that KitKat updated without a problem and my Note 3 runs smoothly and faster than before, but for some there are issues (battery drain, lagging, and performance), which most have been resolved by doing the factory reset.