T-Mobile's HTC One (M8) updated to Android 4.4.3
Besides Android 4.4.3, the update includes improvements to the Camera, Settings, Gallery and HTC Sync manager. Other features of the phone receiving improvements include the BoomSound speakers, the Quick Setting feature, Motion Launcher and the Extreme Power Saving Mode. Enhancements to Wi-Fi, network connectivity and Bluetooth are also included.
You know the drill by now. You can be patient and wait for the OTA update to reach your phone, and receive a notification when it arrives. Or, you can go to Settings, and check for the software update yourself. By the way, the update weighs in at 582MB.