Modern UI with a wallpaper background, substantially more straightforward PC settings, and Windows Update improvements are all very welcome, but my favorite is demonstrated in this screenshot easy to interpret comparison:
|Ctrl + X menu comparison; 8.0 on left, 8.1 on right
This means someone in the Win 8.1 dev team is evaluating power user tools for improvement as well, and I'm very happy to see this sort of improvement. I was initially skeptical, but after seeing these sorts of enhancements I'm definitely looking forward to the final release.
This month has been a bit slow because I'm working on a couple large articles. Stay tuned for some Hadoop and DirectAccess!
Update 10/11/2013: Microsoft removed this from RTM, so.... yeah.