I have developed assessment tools to help judge the difference between the student's work in the group and the substantive material learned. They would learn about what a well functioning group is, the kinds of roles and tasks needed, how to deal with conflict, and a self awareness about their own comfort zones. I look for effort and honesty. I am increasingly impatient with people who don't want to try hard to learn material. I like to see honesty about the about their own level of interest and work.
Good work is clear and easy to follow.
It has substance, not filled with foam or pretention. Generally it is about something that matters. I find myself really interested in the applications and not terribly interested in great theoretical expositions at this point. I am interested in students developing some sense of the big picture. This is demonstrated by the ability to connect across levels in the system.