The most commonly reported problem with the Release Candidate is a bug that causes crashes in IntelliSense when used on a multitouch capable system.  We've released a patch for the RC to address this issue.  You can download it here: http://connect.microsoft.com/VisualStudio/Downloads/DownloadDetails.aspx?DownloadID=26662

If you find anything else broken, please report them on Connect.  We're still fixing any serious issues that are found. 

Brian