The effects for most spells are pretty standard looking -- nothing that will really blow you away. However, this game wasn’t exactly created with extraordinary graphics in mind (I mean hey, it’s a portable after all). The animations have all been upgraded from the NES version as well, and battles now have a look of depth to them, instead of the old look where the characters very well could have been standing on one another’s heads. Overall, I would say that the graphics style is very typical of the more modern 2D RPGs. Perhaps some might call it bland, but I call it tried and true.
As far as sound goes, the game music in Dawn of Souls is exemplary. Every track from both original games have been remixed, and the result is a beautiful sound coming from the tiny GBA speaker. If you have headphones (or even a Nintendo DS), I would recommend using that, as the music is even better in stereo, with a better speaker. In-game sound effects have also been improved, adding a bit more to this re-mastery of the two first Final Fantasy games.