Apple today released a new beta to developers. iOS 8.4 beta was released to developers. The new release features major changes to the Music app, headlined by an all-new design. You can personalize playlists by adding your own images and description. Albums can be played right from the album list. Recently added music is automatically placed at the top of your library. It features a streamlined iTunes Radio and a number of new features.
Apple is expected to launch a new streaming service that features Beats, so this is likely changes in advance of that service.
The full changelog can be found at Apple.