Weighing in at 659MB, the update takes the firmware version to 2.10.720.1, and adds the security updates of Android 4.4.4 to the changes coming from Android 4.4.3. It also adds some updated Sense apps to the device as well. Overall, Indian HTC One (M8) users will enjoy improvements to Wi-Fi, Bluetooth, and their carrier's cellular pipeline. Improvements have also been made to the camera app, the Gallery (Image Match), Settings (Power History) and the HTC Sync Manager.
Because the update is sent out in waves, you might not get it immediately. You can try to coax it out of your phone by going to Settings > About > Software updates. If it doesn't come today or tomorrow, be patient. The update will arrive.
source: XDA, AndroidOS.in