1-It's lacking a language string for emptysubmission.
2-Student sees due date even if it is set far in the future to simulate no due date (which really should be an option of its own). This will totally confuse students.
3-It would be helpful if rather than sort by single columns in the page of students (and their assignments) if the teacher could simply get a filtered list of submitted assignments that they had not graded.
4-There should be a way for the student to save their work in progress and come back to it later, without having to submit it to the teacher, in the online assignment.