Of course the most important: the music. I rediscovered my way of listening to music (no kidding): reading lists, grouped by artist (must say that my old mp3 players were not so pretty basic stuff), and display of large sleeves makes it really all colorful, lively and very attractive.
After the applications I had not bought, because I'm not one "geek" of basic video games. But the enormous range of application made me change my mind: Language methods to yoga, there really has everything you want!
And must, I must say (everything is must but must distinguish a particular thing) .... Itunes U: real education jewelry! This "application" (because it is vastly more than that) puts us free of charge to large US current faculty on any subject, ranging from the ethics of justice (for the faculty of Stanford) until in environmental psychology in college at Harvard. A true general culture jewelry (indeed it's very interesting).
And I have the ipod touch 4 since this morning, so you can imagine what I have left to discover !!
So 20/20!