AT&T is now rolling out its Android 4.4.3 KitKat update for the HTC One M8. It weighs in at over 660MB, and in addition to Google’s latest security patches, it brings numerous Sense 6 improvements — including optimizations for BoomSound and Motion Launch, and Extreme Power Saving mode.

This upgrade comes with build number “2.23.502.3,” and it’s essentially the same firmware that was pushed out to the T-Mobile One M8 earlier this month, and other variants before that. It’s a major release, and it will almost certainly be the One M8’s last KitKat-based update before Android L.

Although it’s labeled “Android 4.4.3,” it actually includes all of the security patches Google made in its latest Android 4.4.4 release, too. In addition, users can look forward to optimized BoomSound, Extreme Power Saving mode, and tweaks for Motion Launch and Quick Settings.

HTC has also improved the performance of Wi-Fi, Bluetooth, and cellular connections — and updated a number of built-in apps, including Camera, Gallery, and Settings.

AT&T is pushing this update out to customers now over-the-air, so if you haven’t already received a notification, you should do over the coming days. You can also search for it manually from within the Software Update section inside the Settings app.

• SourceXDA Developers