I think it was
@ErikGrim who posted a screenshot: nothing aligns on the Radio page. Recently Played text has left padding, Featured Stations does not. The radio stations in Recently Played have graphics, which do not align with Featured Stations graphics. On top of that we have the Beats One banner which doesn't align with anything else on the page at all. The New tab appears to have been changed since I last looked at it a few weeks ago, so I'll give them that. The For You playlists feature a lot of dark grey text on black, which is also conveniently very small. When you go into a playlist you see a lot of text surrounded by a lot of white space. There is no reason for this text to be so tiny. The tiny album covers next to songs make some sense in "80s Club Hits" playlist, but none whatsoever in "Intro to Basement Jaxx" (thank you for this recommendation Apple, I've only got five albums by Basement Jaxx so this will be useful). I don't know if this has been changed but track lengths are sometimes cut off, and you can't resize the column to see them because that would be too useful. I am on El Capitan beta now, so maybe this is not an issue in Yosemite, but the release dates column is also too small, so I get to find out "Red Alert" came out in the year "20..". I find myself squinting to read things on the screen.
Maybe if I'm feeling particularly bored I'll make a re-design of how AM would look if a graphic designer worked on the UI
Edit: Since I can't switch on iCloud (even if I was feeling particularly adventurous with my library) due to owning more than 25k tracks, Spotify Premium which costs me €4.99 per month provides the same functionality as Apple Music which would cost €9.99 per month. So it's a no-brainer for me. I know Apple plan to expand Cloud to 100k tracks, but after reading horror stories here and at other forums I frequent I don't really feel like trying it out.