I don’t care about Ping and I’m not sure about the “new” interface. I like that they dropped the CD on the icon and all, but the only other UI difference I’ve noticed is that they now selectively show album art in the default view… so selectively, I had to go check to see if I lost album art when I brought over my library. I didn’t but it’s just a difference from iTunes 9 to 10.
One welcome feature, however, is the ability to play content right off a docked device even if the computer you’ve connected to isn’t the Sync’ing computer. For example, I plugged my iPhone 4 into a PC that has none of my content. In the past, iTunes would have tried to take over the phone and eventually tell me to piss off; most I could do was take photos off the thing using Windows Explorer. Now, with iTunes 10, I can browse all of the content that’s on my iPhone. Went to the movies section, played one, and it even started when I had last left off.
No matter what else iTunes does to me this release, this one little perk is worth it.