Some of the 4.2.1 features are multi user, quick pulldown settings, photosphere and new camera, new keyboard, new gapps with new clock and timer etc. That's all I can think of off the top of my head but there is more. Also bug fixes and whatnot. 4.2.2 will fix a2dp and some other issues.
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Is lockscreen widgets TouchWiz or 4.2 Android??