I did not have direct experience with the APP used in GE. But the student I mentioned had a positive experience.
Holacracy is a great system. Because Holacracy is an adaptive system and role structure is evolving, GE's real-time feedback probably works better than traditional performance evaluation approaches.
PD@GE is an APP designed by GE. You could check the following to know the user interface.
There are other similar performance management systems like Impraise.