I installed the latest beta over the weekend, upgrading from iOS 9, and am also disappointed with the music app. The design isn't what bothers me though, it's the ability to show only the music on my phone. I know I can do that via the "Downloaded Music" option but it only sorts by album. This is a pain to scroll through when I there is a specific album by a specific artist I want to listen to. If I go into the Artists section it lists everything ever purchased in iTunes. I much prefer the old way of showing only what's on my phone and sorting it by artist. Click on that, find the album, done.
I suppose it's possible I'm missing the function, but I've been through the entire music app and the music settings and see no way of sorting like I used to. Very disappointing.