All our birds like the boings. Moussa the grey has one in his cage, just like the other birds. I think of them like a stairway they can use to get from one level to another in the cage,as well as a comfy perch.
I also have some boings and other hanging toys hanging from the ceiling in the bird room. Moussa loves to go in there and climb and play. Unfortunately, I only let him play in there when the cockatoo is not loose in the room, as she will fly at him and attack him. (I'm hoping that, with time, they will get along better.) In the meantime, we are planning to set up Moussa's own hanging play gym in the living area of the house, where he lives.