Microsoft released the final version of Update 1 for Visual Studio 2013, fixing and improving upon a few key areas of customer feedback such as improved VS support for versions of Internet Explorer before IE10.
The update was announced in blog posts Monday from corporate VP of the developer division S. Somasegar and Team Foundation product manager Brian Harry. Update 1 is only for Visual Studio 2013; improvements to Team Foundation Server 2013 will be included in Update 2.  
The main improvements and fixed issues in the update include:
• IE9 support: The “Debug Managed Memory” feature and IntelliTrace Viewer now support IE9. Visual Studio Online load testing, Load Test Manager and Load Test Results now render correctly with IE9.
Debugger: Fixes screen reader compatibility for the “Debug Managed Memory” feature and adds MMA UI to the screen reader. Updates the “Debug Managed Memory” feature to work on computers that have Windows Internet Explorer 9 installed.
Directed Graph Markup Language: Non-ENU Visual Studio no longer crashes when a DGML document legend is updated by disabling or deleting any item in the legend list.
Visual C++: Visual Studio no longer crashes randomly when editing multiple resources in Resource Editor, and after editing a dialog containing at least one picture control in Resource Editor, the saved project can now be compiled. The IDE now works as expected if there is an unexpected registry subkey.
• Web Tools: Microsoft ASP.NET Web Frameworks and Tools adds editing support for ASP.NET MVC 5.1. Nuget 2.7.2 update fixes the scenario in which certain packages failed when running package restore. Updated SignalR 2.0.1 item templates.
XAML Tools: Improved XAML designer stability in Visual Studio and Blend in a variety of scenarios for all XAML platforms, and addressed an issue concerning packaging of Windows Store applications in which both XBF and XAML were packaged into a Windows Store AppX package when referencing Extension SDKs.
Further information detailing the update can be found in the KB article, and Visual Studio 2013 Update 1 can be downloaded here.