Not sure what kitkat did but it sure improved my 4gLTE reception and not just in the number of bars but in speed. At my work the phone with 4.3 Jellybean would transition between 4g and 4gLTE with speeds around 8Mbps. Now I'm getting 21+Mbps and it stays at 4gLTE with 4 bars. Not sure how a software upgrade could improve what i thought was a hardware or t-mobile issue but it did. I think the battery has improved after several days from updating to kitkat. I thought the battery life stunk right after updating but it seems to have settled and improved. I'm at 50% after 12 hrs of moderate to heavy use with screen on time of 4hrs 23 minutes today. I have to admit i wasn't very pleased with the update due to the suffering battery life but now I'm pleased with the update.