So, I've put up with the changes to the iPad's music app since iOS5 was released without complaining, but I just have to say something. Crap. That is what I think about it. The interface is terrible- the buttons are in the wrong spots from an ergonomic perspective and features are just flat-out missing. There is no consistency in the UI and the shading used to indicate the status on buttons is just terrible. When you choose to listen to an Artist, the option at the top of the list that used to say "all Songs" is just gone. In other words, the only way to listen to all songs by an artist- which I used to do fairly often- is to create a playlist. Lame.
Perhaps the most frustrating thing is that the music app works great on the iPhone. Reason? They didn't change it.