Performance appraisals -- like walking across broken glass, but it doesn't have to be that way. We KNOW how to make them work in the modern world, and Robert Bacal has written extensively on the topic. It's not rocket science but it does require a small shift in mindset from doing things to employees, to working with them, AND focusing on the present and future -- managing performance by clearning out barriers.
There's only one valid reason to appraise and evaluate staff: to improve performance so everyone succeeds, a WIN-WIN.
...and here are the books and tools to make it happen for you and your organization.