This is the start of a synthesis of what we know about Sakai UI Issues
Synthesis of Support Team's from the Community Top 5 Issues: Making sense of Sakai User Support Issues.pdf
Other Sakai UI-related information sources:
Various User Testing Reports posted on the UI DG space: User Testing Results
What Do Users Say? Looking at Survey Results from Different Populations
Usability Evaluation of the Course Management Features of Sakai
Using Sakai in Distance Education - A Case Study