Well yeah. You'll get the real feeling of the interface when you watch it on your ipod. Criticizing the interface when you only have seen the preview is kinda risky..
Nano has only one problem, it's screen in way too small. But now playing looks much better with small album art.
I think I'm going to abandon the large album art and redesign the now playing, then the text will have more space.
And there is volume and progressbar. Just look closer

. And i forgot to add play/pause icon on the previes. It is actually on the titlebar.
I'll think about your ideas, actually I'm not really satisfied with now playing either.
Thanks for suggestions!