This release introduces a number of new features (Documentation forthcoming) but mostly focuses on stability and reliability of existing features, including improved Autoboxing, a greatly enhanced Graph API, a general event listener model and improved access to design element contents.
For a full list of the fixes & enhancements, see the commit list... Compare M2.5 to M3
UPDATE: Squeezed in a patch for this issue here.
http://stackoverflow.com/questions/18589491/org-openntf-domino-exception-on-getdocumentcontext