HTC has started rolling out Android 4.4.3 KitKat update in India for the One M8, which brings improvements in sound quality through the BoomSound speakers as well as camera. LED notification bug which prevented it from lighting up have also been fixed.
The new KitKat update for the One M8 also brings 4G LTE support with improvements in cellular, WiFi and Bluetooth connectivity. The update is 658 MB in size and should be downloaded over WiFi. You can manually check for update by going into Settings -> About phone -> Software update.
Native apps also get an update with the new Android version alongwith several bug fixes.
Source: AndroidOS
