What do you think about performance appraisels?

From your experience –Are performance appraisels good for the worker and for the boss? As a worker, can your grow in your career, take risks and develop useful leadership skills and learn to satisfy your boss by committing to certain goals. Or is it a nighmare senario where you never really communicated with your boss very well and you have no idea about what you really agreed to and the kind of growth you seek was never articulated really. Eventually, you find that the boss finds fault with you and the only way you can sense his ire is by the low salary increase you’ve gotten and he can’t explain to you what you’re doing wrong or right. Give examples of your feelings and examples of what happened to you.