The sequel has waaay more songs (initially) plus has the capabilities to have all the songs from RB1, and, I think the setlist is better (though, to be fair, the sound quality might be gimped or something, we don't know since it isn't out yet and whatnot).
Other didnt really interest me.. How is "the world ends with you" ?? or anything that uses the stylus in a great way?"
World Ends With You is a great game (it's actually my favourite on the system). It's got a lot of customization, so the unique battle system shouldn't ever baffle you, but there is a lot of dialogue throughout the game.
The story seems to be kinda hit and miss with some people, but I enjoyed it.
Other gmaes that you could try that use the stylus a lot are TLoZ-Phantom Hourglass. It's just a continuation of the standard top-down Zelda formula, but a little bit easier and with stylus controls.
If you're a action gamer, I recommend these games:
Castlevnia: Dawn Of Sorrow (sequel to Aria of Sorrow, it's the better DS Metroidvania game between it and Portrait Of Ruin, namely due to the soul system-it's like a demonic Pokemon, almost)
Contra 4 (pretty self-explanatory. Great bosses, crazy levels, and brutal difficulty).
More Weezer and AC/DC, personally. Weezer has some reaaaal good songs that you could sing and are generally more on the "groove" side, while with AC/DC you could totally go all out with the solos and the drum solos and the vocal solos and more solos!