(1) A grid view to let you navigate albums and artists by the pretty cover art. If you happen to listen to your music whole albums at a time rather than via playlists, the new grid view will be perfect for you. For me, it just gets in the way.
(2) The "Genius" music suggester which can create an automatic playlist from your own library, based on a selected track, as well as give you options for music you might like to buy from the iTunes store. The accuracy I've seen so far isn't bad, but the last thing I really need is more options for parting with cash.
One other thing I had a look at was Songbird, an open source iTunes-alike. If you want more customisability, and don't have an established addiction to the iTunes/iPod combo, this could easily be the option for you. It's designed to allow easy music discovery (either free or for purchase), and you can replace the often-gappy album art of iTunes with access to Last.FM (and presumably other sources) instead. It grabs data from an existing iTunes library easily, and plays even iTunes-store-purchased music quite happily. It doesn't include podcasts or movies (by default anyway) but these may well be available add-ons, which would mean it can do anything I already use iTunes for. It recognised my iPod, but I wasn't game to risk synching from it, since some of my content wasn't visible, and could easily have disappeared.
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