Jonathan gave an excellent presentation. He started with some fine examples of (un)usability. And then went along with a little theory (just right!): Usability is characteristic of an interactive system that indicates ease of use and usefullness. It is not 'user friendliness' only. The system should help you accomplish something.
Then Jonathan talked about the goals of the usability testing he carried out. The setup of the testing was that of a walkthrough. The 5 participants involved had to do 17 tasks within Sakai 2.2 (they call it Scholar) and had to articulate what they were doing.
The positive feedback that came back from the users: variety of tools is great, thorough Help system, mechanisms for supporting collaboration (although the test was on the course management features of Sakai).
There was a series of usability problems, that some of us are all too familiar with. One of my collegues, Allard Strijker, came to same sort of conclusions after using Sakai 2.2 in his course. The biggest issues that Jonathan has found: terminology, consistency, sections and groups. In the presentation the problems were shown with video's that were recorded. These video's were very informative (you could see the screen and hear the user talking). Some examples: (terminology) The use of the word Roster is different in the Site Info and Gradebook, (consistency) Removing students or removing sections works completely different.
There were much more video-examples in the presentation. They are not on Confluence, because of privacy regulations. You missed something very illustrative, if you weren't there.