OSNews has an article Celebrating Ten Years of BeOS. The nearest I got to BeOS was a demo at their offices in Menlo Park when I skived off work early on a Friday afternoon a few years ago. All I remember is being impressed by the playing of multiple MPEGs simulataneously, and asking about what their plans were making the OS multi-user. The demonstrator made some very non-committal noises about there being plans for this but it turns out that there was an internal debate going on about it:
Disagreements on how to implement proper multi-user functionality were also present, mostly between kernel engineers, Dominic and Pavel Cisler, the creator of the BeOS desktop/filemanager, Tracker. Pavel came from General Magic and later worked at Easel developing Gnome's Nautilus while today he works for Apple on Finder. Half of the engineers were citing kernel/fs changes and other half filemanager ones. Multi-user functionality was finally implemented but was never shipped because it was breaking a lot of apps that were created with single-user in mind (BeOS already had about 1500 applications at that point) and that was a business risk Be didn't want to take.
The lack of multi-user support effectively killed off my interest at that point.