AlbumMixer is a pure itch-scratching app: I wanted album shuffle badly enough to pay Apple for dev program membership. Now I'm letting the market pay some of that back to me, if it wants to. I might never write another iPhone app, unless I happen to come up with a cool idea that's well-suited to the medium.
Getting back to 1.2, it won't be possible to differentiate the UI changes from the significant feature changes: the filters were the single feature that users of 1.0 requested, and I couldn't see shoehorning them into the single-view UI. I would expect the new feature to have a larger effect than the new UI, but I can't see a way to test that theory.