lighter, harder, smoother, less heat, less friction = less power robbed + longer lasting than steel.

but seem spendy to me, unless you are ultra elite. $300 for wheel bearings, another $200 for the BB.
Plus you gotta be running some high end stuff to be there.

I read from FSA that a Record BB spining at 100rpms @ 400w consumes 0.6W and the ceramic bearings would consume 0.02W <for what it's worth>