Offering higher-quality playback, it has become famous among audiophiles, alongside its biggest competitor, Pure Vinyl (and now Pure Music).
For a while, that was Play and one or two others, but then Amarra came on the scene. Though iTunes wiped out the need for competition when it was introduced, it has become a huge, multimedia and store program, leaving many people wanting something simpler. There seems to have been an explosion lately in 'audiophile' music players for Mac OS X lately.