Expanding the appropriate file download and running Setup.bat will uninstall any old NORMA version and reinstall the new NORMA components. Visual Studio instances should be shutdown before running setup, and Vista/Windows7/Windows8 users should either launch the provided SetupVistaOrLater.bat or explicitly run Setup.bat as an Administrator. The release includes modifications through changeset 1518.
The May 2013 release contains fixes for bugs found since the January 2013 release, including fixes for missing internal constraints on the Constraint Validation page in the generated HTML report, some minor changes to the relational view, targeted verbalization enhancements, and a fixes for a couple of crashes.
Details are available in the included Documentation\Readme.htm installed with NORMA and in the SVN change logs on sourceforge. A copy of the readme has also been posted on sourceforge so you can review changes before you download the binaries.