Microsoft Visual Studio 2013 Update 4 RC can be downloaded at: http://www.microsoft.com/en-us/download/confirmation.aspx?id=44545
It contains many new features for an update: http://blogs.msdn.com/b/webdev/archive/2014/10/16/announcing-new-web-features-in-visual-studio-2013-update-4-rc.aspx
The thing I like the most:
Support for custom elements, polymer-elements and attributes
We no longer validate unknown attributers for custom elements as there will be many custom made tags in different frameworks. So there will no longer be squiggles under the unknown elements.