We are the way we are mainly because we tend to like ourselves that way. However we also live in a society which has people who can look at our behaviour in another way, which we might not have considered to begin with. So giving others a chance to express their opinions could help to understand the way we are, from multiple perspectives and hence improve our own living.
Criticism is something which can get anyone irritated. Wisest thing you can do to ensure that you do not react and also make most out of criticism is to ask the person to explain the scenario which made him/her criticize you. This way you would get a picture of why the other person thinks the way he/she thinks and respond after understanding the exact meaning and intent of criticism. This should help you gain control over overreaction towards criticism.