http://www.collingwoodsearch.co.uk/our-insights/recruiting-retaining-talent/to-appraise-or-not-to-appraise-this-appears-to-be-the-current-question/  In my experience performance appraisals are effective or ineffective dependant upon the line-manager conducting the appraisal.  To enhance engagement, motivation, morale and performance employees should not leave the meeting feeling deflated and under-valued.  Yes, difficult conversations, where required, need to take place but this should be done constructively with examples of how performance can be developed and improved, and finished on a positive outlook.