the environment has become incredibly toxic because of the forced ranking. I have seen people getting low rating for being on bereavement, when switching jobs, for taking vacation. I have seen people crying, because they felt the poor rating was not deserved. I have seen the LL2 level downgrading, because there were insufficient low ratings. Often playing favorites instead of relying on actual performance; even switching rankings to give a favorite a higher bonus.
I have seen a manager lose team members who were given to another manager. And then being dinged for not hitting numbers and he was basically told to find a job elsewhere, while the other manager was promoted without having to actually deliver.
I have seen people being absolutely targeted and harassed. Always looming the performance rating over their heads without an ability to actually improve.
On the other hand, the favorites do not need to deliver and are getting rewarded for incredibly low performance. It is all a popularity contest.
Exactly what @fk+1m3s4a1cp said.