The new update is named as Window 8.1 Preview so it still not stable version. But people can give hand to it by installing it via the windows store.
- New Start Button - Windows 8.1′s Added new Start Button which is more of a shortcut to the Start Menu - in with the little added colorful icons.
- Redesigned Windows Store - All the built-in apps were improved with redesigned store which shows the detailed lists of top free apps, new releases, and picks for you on the homepage.
- Better Search - Updated search with better result powered by Bing,combines the internal search as well as the web, internet search results.
- Tile sizes in Start up - The addition of two new tile sizes: large (really big) and small (really small). "For example – I have the Weather app as a big tile and it now shows me today’s and tomorrow’s forecasts. Big tiles can have much more information on them,"
- Internet Explorer 11 - The next version of IE is packed with more of a touch browser as said my MS, with better page load and speed than previous one.
- Cloud Stores - With Skydrive Windows 8.1 allows direct saving acessing the files from the clou storage provided by Microsoft.
The size of update is 2.44 GB, which can be installed from Windows store for which window 8 is required to be running OS. Get the preview from here.