The HTC One for AT&T is now receiving the Android 4.3 Jelly Bean software update. The carrier started rolling out the update yesterday, so it may be awhile before it reaches all the devices. You can check if the update has arrived on your device manually by heading to setting for AT&T Software Update and then selecting the Tap Check for Updates option.The update is being offered over-the-air, and your device will automatically reboot once the update is complete. It is recommended that you are connected to Wi-Fi and your battery is fully charged before you initiate the update.
Android 4.3 is an incremental update, but still it brings a few noticeable improvement. It delivers more toggles for quick access to oft used settings in the notification shade, and you can add widgets to the lockscreen.
HTC has also taken the opportunity to update BlinkFeed, which now adds Instagram support, allowing you to keep track of your friends updates. Additionally HTC has also made some improvements to the camera apps which now allows you to lock focus and exposure. HTC Music and HTC Zoe and other photographic features have been improved.
The HTC One still holds the flagship position for the company offering an excellent build quality coupled with a stellar performance. Its specs include a 4.7 inch touch display with an FHD resolution, up to 64GB of internal storage, a 4 megapixel camera with UltraPixel technology which is capable of 1080p HD video capture, a secondary camera for video calls and a 1.7GHz quad-core processor with 2GB of RAM.
source - CNET