Today I've made Amarok2 use the new Oxygen icons from SVN trunk. Have a look:
I'm rather fond of Oxygen; I think it's an improvement over Crystal, and definitely feels refreshing. Unfortunately even Oxygen can't solve some of our fundamental problems with icons:
Amarok needs many very specific icons, like "Update Collection", "Cover Manager", or "Visualizations". We would need someone to create these icons for us.
Our release cycle is independent from KDE's. Sometimes we introduce a new feature that needs an icon. Relying purely on Oxygen, we would need to wait for the next KDE release to get a suitable icon.
The biggest problem: KDE allows users to switch to alternative icon themes. Most likely they're incomplete as far as Amarok is concerned.