Not only does the DS have FFIII, it also will have FFIV remade for it, and more RPG's like FFTA2, FFXII:RW and Dragon Quest IX. But you know, aside from that there's some other good games out and coming out for it.

Things like New Super Mario Bros., Mario Kart, Diddy Kong Racing, Castlevania, Pokemon Diamond/Pearl, and loads more are worth getting.