Great start!
Process-wise, I'd recommend showing this to someone who hasn't seen the UI and ask them to explain what they see (or how they'd start doing different tasks) — this is sometimes called "guerrilla usability testing".
Also, I'd use more real data to see what happens to the layout with longer song names, artist names, genres, etc.
On UX/usability level things that I'd pay attention to: do users realize song is a drop-down and song name an input? What do icons such as "P" and "P + circle" mean? Which elements are clickable and how to make that obvious?
On UI level I'd try to reduce clutter to make the design more clean to reduce extra load from the user to perform their tasks. So: just one typeface, more neutral zebra row color (or remove it), remove the note icons, remove vertical bars next to album art, etc. And then, if you like, add the visual matrix printer motif back when all extra clutter is removed. I'd avoid also strong border colors and use subtle background colors, and try to be uniform with paddings, borders, etc.