The Phenomenon called 'Appraisal'

Appraisals happen across all organisations, and do really "happen" in some organisations, with juniors being almost threatened by their appraisers with the sword called appraisal. How do we ensure that the seniors are not being taken away by personal relations with their juniors? 360 degree review appeals a lot to me rather than the senior appraising the junior. It happens at times, that we may be even appraised by a person for the particular appraisal year by a senior of us, who knows us just for a small period in the whole year. How can we ensure transparency and absolute appraisal when the "professionalism" exhibited by the senior working class is an absolute mockery? during a dicsussion on appraisals, one another friend of mine, threw a very interesting observation. 'In a 360 degree review, n people appraise their managers, so it makes it a much more effective appraisal. more the sample space, better would be result of the outcome.' So, I would be a strong advocate of 360 degree reviews.