How Honest Should I Be If I'm Asked to Provide Feedback Regarding My Supervisor's Performance By My Supervisor?
If your supervisor or manager specifically asks you for feedback about his or her performance, you should indeed be honest, but you also need to be constructive, just like your supervisor should be if commenting on your performance as a regular employee.
Being constructive with feedback means you should be as specific as possible, and focus on one or two things that your supervisor could do to be more helpful to you in terms of getting your job done. Remember that you shouldn't "kitchen sink" or comment on too many things. That's critical. Also, it's better to provide feedback about behaviors and actions rather than personality traits. Commenting on a manager's personality characteristics is likely to result in defensiveness, just as it would if your personality was the focus on such comments.
So, honesty is good, but so is being smart and realizing that managers are human too. Don't use the opportunity to bring out the axe you want to grind.