It's great PR. At least, some might think that. For Apple, this is not about money. However, it does speak to how Apple can maneuver more quickly under Tim Cook. It also says that Apple feels at ease in bending some rules or doing away with them when it feels it will not have adverse affect on the company's bottom line. This u-turn certain won't hurt Apple's image.
To be sure, this will have a long-term implication in the music industry. See, there was mention that Apple would pay the artists during the free trial period. No mention whether the labels would get a penny. Perhaps, this was Apple's move all long. Playing a couple of moves ahead of everyone else.
Perhaps now, Swift's music will not be a part of Apple Music's streaming service while it continues to be absent from Spotify and others' music library.