When grading a submitted assessment in Tests&Quizzes, you have the ability to leave grader comments on both individual questions and on the assessment as a whole.
The student can see grader comments on individual questions when he or she reviews the assessment (if that feedback type is enabled). But there's no place in Tests&Quizzes where the student can see the grader's comment on the assessment as a whole.
This could potentially be a big problem in production - instructors will leave comments on the Total Score page, where the comment field is prominently displayed, and expect students to be able to read them.
Marc suggested generating a TOC page that includes the grader comments as part of assessment review. It might be simpler to just put a field with the comments at the top of the review page, though. Marc, Lydia, what do you think?