With my own students I've seen time and again how powerfully helpful it can be for students to give each other peer feedback on their music.
Not only does it help the student to get feedback on their music it also exposes the entire class to the ideas and choices of all students. I've seen many times how discoveries are made based on something a student heard in a classmates' piece.
To help facilitate this important interaction there is a Module called "Discuss" with an assignment named: "Share Your Composition and Give/Get Feedback"
The assignment will lead students to a Discussion where they will post the embed code of their Noteflight score. They then are directed to leave supportive, thoughtful and helpful comments on at least 3 classmates' pieces. We also encourage them to respond to the comments about their piece.
Here is a sampling of comments from some of my students (5th graders):
As you can see, the act of writing the comments helps each student to contemplate and articulate the various musical concepts explored in the course.