Four suggestions:
1. Sort by Artist > Album in the iOS app. You already nailed this feature in the OS X app (in Loop view at least). Just bring the exact same thing to iOS so I can browse Artist > Album by Year like the stock iOS app.
2. Caching of content/artists/playlists in the iOS app. I already bought a year of Loop and was very surprised to see that the iOS app is streaming only. Almost every other major streaming/cloud music solution allows you to download content, I kind of just expected it to be there. This one is kind of crucial as without it I have no music on the subway, which is easily 75% of my music listening time.
3. Allow us to turn off breaking up of albums by file format in both the iOS and OS X apps. Many of my albums have an AAC track here or there, doesn't make a difference to me. Visually (and for continuity in an album) it's really frustrating to see a bunch of duplicates. Don't make me convert an already lossy file to another format just for organization's sake.
4. Metadata editing in the OS X app. Least important, but it would be nice.