With 1.5 several new tools have been introduced into Sakai. There is a more configurable help system, a syllabus and a presentation tool, and integrated access to the Samigo "Tests and Quizzes" system.
With more tools comes a bit more complexity.
The default storage mechanism is now a hsqldb database. The xml storage format is no longer supported.
With 1.5.1 the Samigo tool is now fully integrated with the QuickDemo distribution. The QuickProd distribution has the Samigo code integrated for deployment into Sakai. There have also been over 60 bug fixes since the 1.5.0 release.