To start with, the Windows 8 app looks great. I was using it today at work to do some music streaming. While doing so, I noticed that there are some glaring missing features for music.
1. No quick way to get to now playing. You must first go Home then click on Now Playing. There should be a button added to the app menu.
2. Shuffle feature for playback
3. Playlist creation and use
I am happy to assist with testing if needed.