How cute... my Amadeus is TERRIFIED of the vacuum and will run and hide behind all of my long formals in the closet when it's running. Yet when it's not running and is just sitting in the corner of the living room, he'll come and LAY on it!!!
Sebastian is somewhat indifferent to it. He doesn't really want it near him and he'll move away, but he'll stay in the same room sometimes.
From my experience it seems most cats are at least apprehensive of the vacuum cleaner.