I installed the Music App. It's "slicker" than the current Music App. It looks and feels like what you'd expect the next Music App to look and act like. It feels faster navigating than the previous Music App.
I tried it, but couldn't figure out how to log in to my Music account.
I was wondering the same thing, but while listening to a song after I first installed the new Music App I got a notification on screen asking to link my gmail account and it did.