In less than 2 weeks from now, October 18 to be specific, Visual Studio 2013 (not in RC) will be released as RTM version. The official launch will be November 13, if you are interested.
Visual Studio 2013 brings along with it the new versions of .NET Framework (4.5.1), Entity Framework 6, MVC (5), Razor (3), Web API (2) and SignalR (2). It has restructured the project types in one ASP.Net location (not as in previous versions) and baked in TypeScript and Bootstrap 3 (responsive css).
Both the editor and the TFS have been enhanced with features like XAML Editor, Browser Link, Peek Definition, Code Lens and Work Item Charting.
If you are considering starting a new MVC project, you better start with the new version, not only because of the new features, but also since the upgrade from version 4 is not straight forward. You can find details on upgrading from MVC4 to MVC5 in this blog post.
For additional details on new VS 2013 features, check Somasegar’s Blog post and this Channel 9 interview.
To learn more about One ASP.Net, check this interesting blog post by Scott Hanselman.
Pricing will be similar to the 2012 SKUs except for an offer to upgrade from 2012 Pro for $99 through January 31, 2014 and $299 afterwards. Pricing details can be found in this VS Magazine article.
If you have already installed the preview or RC version of any of the VS2013 SKUs, feel free to check the MS compatibility page for VS 2013 for upgrade paths (toward the end of the article). According to that article, you have to un-install preview express first and no upgrade path from mismatching preview and RTM versions (ex. pro to ultimate).