I personally love everything about iTunes 10. The look is sleek and the logo is a nice change from having the same one for years. People are blowing it way out of proportion
The icon isn't a big deal to me. I like it, and if you don't, it's a quick fix with CandyBar or what have you. It's the grey interface that feels like a step backwards.
Overall positive. I like the changes to the sidebar, the lists and the toolbar at the bottom. I don't like the new volume slider 'ball'. I'm indifferent towards the icon.