One of the posts that consistently generates traffic to this site is this one. It was written in response to a Seth Godin post on the art of Giving Feedback.

Now whether you are a giver or receiver, criticism can be hard to take. You can feel slighted, victimised, angry or insulted. Sometimes the blood rushes to your face, your hands or to your feet … criticism is one of those things that creates an emotional AND physical response.

BUT … it is not just the receiving of criticism that is difficult. Giving it can be challenging too. Even those in positions of power can be clumsy in delivering feedback … So, if you DO have to provide feedback, here are some tips:
1) Be honest but not brutal
2) Don’t embellish or change the message part way through
3) Do it earlier rather than later (don’t wait until things are very bad)

Oh, and on both sides … be gracious under pressure.