The new style is great--rounded corners everywhere give the interface a more unified feel. 2 minor things which may be beyond the scope of your question as they exist in both versions (using Win 7):
1. Connect/Share button doesn't match. It's missing the separator and the arrow isn't centered. Side note: I'd rather have the submenu options show up on mouseover rather than clicking the little arrow or have all the submenu options available as toolbar buttons.
2. The yellow highlighting to show placeholders for coverflow/book details/tag editor is distracting. Ideally, I'd rather be able to combine some/all of these into a single sidebar.