My assoc uses thearbiter, and Ive found it to be a great tool, and
AFAIK our assignor thinks its great as well. Being able to project my schedule and block-off times well in advance and do game reports online has deconflicted *many* a schedule. I think it works well.
But then, I can see that people unsavvy/uncomfortable with the Internet or web-based programs could be intimidated. Our assoc has at least 2 classes (as needed) to teach the basics of the program at the start of the season.