You can see a feature demo here, which describes the features with screen shots:
http://learn.humboldt.edu/course/view.php?id=21&topic=6
And if you want to try it out, you can go here and login as test/test (teacher view, just click on grades to see the gradebook). Test is a non-editing teacher, but you can see and change things in the gradebook (since the gradebook just pulls from the standard module's grades tables, it is entirely non-destructive, no actual grades are changed, just the way they are calculated)
http://learn.humboldt.edu/course/view.php?id=21&topic=6
It all works, so feel free to login as one of the demo students, take some quizzes, and then go back in as teacher and play with the weighting settings, etc.
This site may show some odd behavior as we are testing fresh code on it