The IPAB was a terrible idea. They are an unelected panel that recommend spending cuts based on an arbitrary scale. It has too much power — if Congress doesn’t pass legislation meeting their reduction rates — Medicare spending is automatically cut.
Medicare spending needs to be reined in one way or another, it's increasing every year at an unsustainable rate. The IPAB ensures that the necessary cuts happen, even if Congress can't agree on a bill that would temper spending.