I think it is mostly designed to document issues with low performers to have as evidence for their eventual termination.
I try to use it to improve and there are some suggestions that help and in theory it can better align manager and employee expectations. I use it to explain my long term career goals to my manager so he knows what I need and he can relate to me if he wants me to make any changes to reach the goals of the group and company.
I mean, if you worked here you would learn not to expect much. The managers are always trying to push responsibilities down to the employees. It's to the point where the employees might as well do the manager's job. Oh wait, we have senior devs in a new chapter lead model that do half people leadership and half coding... what a mess.
At my first company we had an open salary and review policy. You could read anyones up to ceo level (6000+ employees). This was the best structure I've worked in, but it might not work for everyone.