The bottom line
This update has gone a long way toward making Windows 8.1 appear to be a single operating system rather than two OSes bolted uncomfortably together, notably by having Windows Store apps behave more like desktop apps and having the taskbar available on both the Start screen and desktop. And having Windows automatically boot to the desktop on new, non-touch PCs is a big step forward as well.
Still, I don't think Microsoft has quite nailed it yet. Windows Store apps still look and work differently than desktop apps -- they tend to be more graphically oriented and have far fewer features, just what you would expect in a touch-oriented tablet apps. They still can't be resized or run in separate windows on the desktop. And there's still no Start menu.
If those two issues were fixed, Windows 8.1 might finally seem like a single operating system that can shape-change according to whatever device you're using, rather than two different operating systems coexisting on the same machine.
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