As an example, refer to a previous article I wrote about the wonderful song, "Paternal Horn" from Nights Into Dreams. Compare that version to this one from the Game Boy Advance title, Sonic Pinball Party.
Yeah, not exactly great. It really tries to be great! Like gosh darn it does it try! But it ultimately fails pretty hard.
And then the Nintendo DS could do something like this:
This is the song "An Empty Tome" from the game, Castlevania: Order of Ecclesia. The Castlevania series has always been noteworthy for its incredible music, but this piece ranks among the very best the franchise has every produced. You can pick out the various instrumentation they tried to simulate quite well; the piano like keyboards, the jazz inspired drumming, chimes, strings; it's all there in synthesized form, and it sounds remarkably strong, especially for being from a handheld gaming console.
"An Empty Tome" carries an air of darkness and mystery, just like any Castlevania game should given its Gothic setting and imagery. Composers Michiru Yamane and Yasuhiro Ichihashi deserve a world of credit for being able to construct something so vibrant and evocative. I still remember the first time I was playing this game and hit the song; I was quickly taken aback by how great it was. It successfully arrested my attention enough to where I wanted to go back to the area the song played in, just to hear it again. That's a sign of strong musical composition in a game.
There are a number of other great songs from Nintendo DS games, but "An Empty Tome" transcends the console it was created on and stands as one of the better gaming compositions in general.