I think that there should be a plain font and special font file, because often when you use a different font, the whole theme lags when scrolling. Also, try using this as inspiration, it's a really nice one that I found the other day.
the next simplicity_ iriver
This one was by the same user, but not as good:
the next simplicity_ iriver
I like the general menu, and the little spinning thing, and the fact that everything important is placed where it can be seen. I'm pretty sure that it had full screen album art as well. And if you can figure out how to put stars on the Now Playing screen, please tell me, I've been trying to find this out for a while now.