The iTunes 12 interface has a lot of changes, one of which is the font used in its display. iTunes offers several choices of sizes for fonts in list views, and has for a while. With the new fonts, iTunes has also adopted a new way of changing the size.
To change the size of fonts in list views, go to iTunes > Preferences > General, and choose from the List Size menu. Here’s what an album in Songs view looks like in the three different sizes, small, medium and large. (They’re all scaled the same amount from the original screenshots.)
You can notice two things here. First, the album art changes size as you change the list font size; the two shouldn’t be linked.
But also, the change from medium to large fonts only makes a small difference in the font size, but there’s a big difference in the link spacing. It looks way too airy in large size, but I do need to use the large fonts, especially with my new 5K iMac, as the relative pixel size of the interface is smaller than it was on my 27″ Thunderbolt display. This said, given the quality of the display, I may be able to use the medium size.
But I think Apple could have done this better. I don’t understand why the artwork changes size; there is a size slider in the View Options menu, and if I want to change the size I can do it there. (But not that in each of the above screenshots, the artwork is set to the largest size in that menu.) And the font itself? It should be larger in the large size, with, perhaps, a bit less line spacing. Extra spacing can make fonts easier to read, but in this case it looks like it’s too much.