My sister works for a company where the 3 monthly performance reviews are completed by her peers, the team she manages and also the company's clients in order to give a full and fair appraisal of her performance. The idea of this simultaneously fills me with dread and also makes sense. The traditional annual review completed by your boss seems archaic given the change in how many companies operate but how do you feel about each of your co-workers having the opportunity to influence whether or not you get promoted or receive a pay rise? That is a lot of power to give to employees, many of whom may not really be reviewing performance but basing their review on whether they like you or not. That said if the number of reviews are sufficient it should dilute any bias. It's definitely a good thing to see companies attempting to update their processes.