I can’t say much about iTunes 12, a beta of which is only available to the million-plus people who have access to betas of OS X 10.10 Yosemite. I can’t publish screenshots, since I’m under NDA, having a developer account. But I can comment about what I’ve seen on many other websites about iTunes 12.
Apparently – and I can neither confirm nor deny this – iTunes 12 eliminates the sidebar. If you’re a long-time iTunes user, you may have a weak spot for this sidebar, which gives you access to your different media libraries, connected devices, shared libraries and playlists, all at once.
I like using the sidebar, and even the column browser, as you can see above; that’s the default way I display iTunes. With iTunes 11, if the sidebar is not visible, you can display it by choosing View > Show Sidebar. And if the column browser doesn’t show, you can turn that on by choosing View > Column Browser > Show Column Browser.
I’ll miss the sidebar, and I wonder why Apple is removing it. For those who use it, it’s a convenient way to access much of your iTunes library. According to screenshots published on a variety of websites, there is no longer even a drop-down menu at the top-left of the iTunes window when the sidebar is hidden; you access the various libraries and devices by clicking icons in the navigation bar.
This may be more efficient, and the lack of the sidebar offers more screen space to display content, but I still think the sidebar is a useful tool. Maybe Apple will add it back by the time iTunes 12 is released. If not, I’ll miss it.