Get your update today! Windows 8.1 Update and Windows RT 8.1 are now available for free Windows Update. Follw the instructions from http://windows.microsoft.com/en-us/windows-8/install-latest-update-windows-8-1
The updates are already available few day back to MSDN and TechNet subscribers.
Read more the Windows 8.1 Update review from Paul Thurrott’s WinSuperSite http://winsupersite.com/windows-8/windows-81-update-1-review