From Apple’s release notes:
The iOS 8.4 Beta includes an early preview of the the all-new Music app. With powerful features and an elegant new look, enjoying your music is easier than ever. This preview provides a sneak peek into what we’ve been working on, and what’s to come — the music is just getting started.
I don’t remember seeing redesigned or new features described by Apple in a beta as an “early preview”. The “beta” label implies that it’s an early look at a forthcoming feature anyway, and it’s missing the most-rumoured part: Apple’s new streaming service. This seems peculiar, as if it’s a hint at a different strategy.