So grading groups are nice. I can assign an individual assignment to a particular group of students. (read - special needs, advanced students, etc)
Where this falls apart:
Working in groups - if a student is working in a group using project-based learning, or anything where a GROUP is submitting an assignment, it is completely useless because if I apply a grade to one submission, we should be able to have that grade copy to the other members in his group.
PLEASE have a check box that says "GROUP GRADES AND SUBMISSIONS" where the student's submission will automatically be linked to the group, as well as the grade I apply.
Alternately, separate groups so when I apply an assignment, make it "Assign to Groups" where any student who submits it will show up as grading that group, rather than grading the student.
Other than that, it's pretty useless.