When you say 'it' do you mean the interface or functionality? Because personally I didn't think the interface was in need of an improvement at all. If they're going through this trouble of updating the interface why don't they give me the option to increase font sizes in list view? That would impress me a lot more than an interface redesign. I'm not saying it's bad but as you can tell I prefer functionality improvements over interface adjustments ... luckily this update did come with some functionality improvements.
I do mean the interface. iTunes looked like some load of bloatware from the early 2000's. It's 2012, not 2001. Tables are a thing of the past. Software is being more organized in a visual way, which I think iTunes 11 has successfully accomplished with it's album view.