Lukas Mathis analyzes the new iTunes design:
"You can’t make a complex application simple by adding a veneer of simplicity on top of it. in fact, that will just add to the confusion, because now you’re sending the user misleading signals about what’s really going on. Apple promised a «dramatically simplified new interface». They were right; the interface does look more simple. Unfortunately, this just makes the rest of iTunes all the much worse."
Stephen Hackett linked to that same piece, adding this:
"Even after a couple of weeks of daily use, I’m still uncomfortable in the new iTunes."
I agree with both of them. I've been playing around with iTunes 11 for a couple days, and it's been one of the least enjoyable experiences I've ever had with the app. As someone whose history with iTunes has mainly taken place on Windows PCs rather than a Mac, that's saying something.
I'm lucky since I rarely need to use iTunes anymore now that I'm reliant on streaming services like Spotify, Netflix, and Hulu, but I sympathize with anyone who has bought most—if not all—of their content from iTunes.