The problem with all performance review systems, as I saw in the military, is that they quickly become inflated. By that I mean "outstanding" becomes average, "average" becomes poor, and "poor" means you're about to be fired.
In the military it was worse, as your performance rating gave you points towards promotion and getting anything less than the max could screw you out of a stripe (and thus a pay grade). Fortunately, that never happened to me, but I knew one or two guys who *did* have that happen.
I think one-on-one meetings your immediate boss are generally sufficient. Of course, I've never been a manager, so what do I know?