Let’s Compare! Final Fantasy III iPhone Vs. Nintendo DS
Final Fantasy III on the iPhone is indeed based on the Nintendo DS remake of the game. However, Famitsu point out that Square Enix have redone the artwork for the iPhone/iPod Touch version, slated for release in March.
Compared to screenshots of the DS version, the textures in the iPhone re-remake are definitely higher, while portions of certain textures have been redrawn or made more detailed. Here’s a quick comparison we threw together so people can tell the difference: