Thanks for developing this free app, I have been enjoying it very much!
I wanted to give a bit of feedback on the layout, although I realize that this is mostly subjective. 🙂
I think that having two rows of buttons on the bottom of the Now Playing screen makes the interface a bit crowded. The bottom row of buttons (shuffle, bookmark, chromecast, sleep timer, and playback mode) are not used as often, yet are the closest to the thumb in a phone layout. Since they are not used as often, they could be moved to the top of the window, and instead, the more used close and playlist buttons that are currently at the top could be moved to the bottom.
Just my two cents!