Dear Sanpunu
First thing first the reason for 360 degree success and blast is not that its just the performance appraisal method but because its basically the performance management system which is a continuous process whereas appraisal is done once in a year, it comes under PMS, the funda behind its success is that its the one of the new modern system which reduces the error in appraisal to minimum. under appraisal either you are rated or graded but under 360 you are judged from all sides you are linked to- peers, subordinate, senior, customers(internal or external),and even self appraisal is included. Its not just your job performance, its not just your job/target achievement its how you achieved ( for example you delivered your target but how did you cheat the customer which might cost company in long term) that target, your behavior is been continuously noted not at the last moment just few months before the appraisal but in complete year, plus every thing is documented in forms in particular format so the difference could be visible and the transparency in system will help you analyse what you think you are and how company see you, employee and employer can easily find out the gap (this is how training need is analysed) in achievement and desired result. additionally company use this system in customized form according to there own need, you can mix it with management by objective ( KRA, Target). 360 deg not only judge employee but in overall judge the company(what kind of employees we have, are they right for us, its helps company improving its performance by improving the employees performance ) there is another system balance-scorecard which proved to be another major successful system in terms of PMS
hope it helped a little
Regards
Vandana Malik