The Pope is staying in room 201, which is a unit reserved for the Pope and special guests. The Vatican's spokesperson, Father Federico Lombardi said the Papal apartments are ready to welcome Pope Francis, but apparently the Pontiff says he's quite comfortable at the Casa Santa Marta, so he will continue to live there alongside other priests and bishops.
Just a few days after being elected, the Pope was given the keys to the Papal apartments, but he didn't actually move in. The ceremony included cutting the red ribbon that rapped around the doors and the breaking off the seal.
Whether or not the Pope will eventually move to the Papal Apartments is yet to be seen.