If you want to know what's new, the official Windows Blog has a good recap. A lot of folks will surely appreciate the ability to bypass the Start screen and boot directly to the desktop. An old-school Start button can be added to the taskbar, too, but there's no Start menu attached. Microsoft appears intent on directing everyone to its oversized Start screen instead. Ugh.
Users at least have more freedom to tweak the Start screen in Windows 8.1. There are more tile sizes, and the background can be changed to match the desktop.
On the multitasking front, up to four Metro apps can now be run side-by-side on the same screen—and with adjustable window sizes. That requires finding four Metro apps that you want to run at the same time, of course, but I digress. Win8.1 also improves support for Metro apps on multi-monitor configs. Sharing and search are supposed to be integrated better into the OS, as well.
In addition, Windows 8.1 brings substantial updates to several of Microsoft's applications, including Internet Explorer, Mail, Calendar, and Xbox Music. And there are new apps: Health & Fitness, Food & Drink, and Help + Tips. That last one may prove invaluable to users getting their first taste of Metro. As Ars Technica points out in its look at the new OS, Windows 8 provided very little instruction for the uninitiated. I hope Win8.1 does a better job of explaining how to navigate the UI.
Even though Ars notes that there's still room for improvement, the site calls Windows 8.1 "the operating system that Microsoft should have shipped." Grabbing the update seems like a no-brainer for current Windows 8 users, but I'm not sure the OS does enough to attract those clinging to Win7. There's always Windows 9, I guess.
Personally, I'm more interested in the wave of next-gen devices that will have Win8.1 pre-installed. One of those is set to arrive at the Benchmarking Sweatshop today, and we'll have more to tell you about it very soon.