HTC created a special Dual Sim (http://www.gsmarena.com/htc_one_dual_sim-5498.php) version of its HTC One flagship, which is limited to several markets like India, China and Russia. Strangely enough this is also the first One variant to receive Android 4.2.2 (not counting the Nexus Edition), the worldwide version of the flagship is still on 4.1.2.
The update brings a number of improvements to both the Android base and HTC's customizations. There's a widget-enabled lockscreen, quick toggles in the notification area plus smaller enhancements like rearranging homescreen panes, battery percentage in the status bar, options for the Home button to remove the on-screen Menu button.
The Camera and Zoe apps were improved too