Loving this so far. I've played from the beginning up until the part where you first get to fly the airship around (so a decent chunk of the World of Balance). For the vast majority, the sound fixes are spectacular.
The only slight flaws I can hear were mentioned by someone else- some of the sound effects seem slightly "off". Time/SpaceMage already mentioned some examples. Much better than the unaltered version, but perhaps could do with some minor tweaking. Sounds I noticed as seeming off include the noise of defeated enemies, as well as the save point chime (the one when stepping on top of the save point, the menu save confirmation chime seems fine). I don't know how to really explain the issue with the save sound, you'd have to hear both versions side by side to get an idea.
The defeated enemy (normal enemies, not bosses) effect sounds like it may be either a pitch or volume issue, it's supposed to have a sort of bassy rumbling noise overlaid with a higher pitched sound. The high pitched noise sounds a bit like a cymbal, but with a hissing/whooshing effect to it. All that is audible in the restoration hack is the rumble, I can't make out the higher pitched noise. If it's there, it's barely audible and should be much louder. Again i'm unsure if the pitch is off, volume is too low, or what... Here's what it's supposed to sound like (probably better to listen than to have me attempt to explain a sound)-http://www.mediafire.com/download/66gp8g7v2iwcfx2/2DMonsterDeath.wav
I'm only just now grinding for spells, so i'm unsure if any of their sounds are accurate. I guess I could have just downloaded a completed save file to test them, but i'm currently playing through the game normally and naturally for my own entertainment.
The slowdown is drastically improved as well. Not gone, but a LOT better. The mode7 parts used by the chocobos and Serpent Trench feel extremely smooth and very fast now, similar if not the same as the SNES version. Airship still has some lag, but still far better than it used to be (feels faster and more responsive to control as well). Intro scene approaching Narshe is also extremely smooth now.
Tales of Phantasia anyone???
ToP GBA is in far worse shape than FF6A. The visuals were massively compromised as well as the music. At least with FF6, the most major problems were related to palette, sound and some framerate/slowdown problems. A palette restoration has already been made, and the sound restoration fixed both the sound and at least dramatically improved the slowdown. Phantasia is some odd mishmash of the SNES and PS1 versions, palette and sound issues are the least of the problems (at least those could be fixed). A lot of visual effects were just removed outright. And the battle system is much slower and more choppy (and I suspect in this game's case the slowdown and low framerate was intentional and hard coded into the game so probably won't be fixable). It feels like a big janky mess overall, probably not worth messing with.
I don't know if Bregalad will do any more sound hacks like these, but there are other SNES-to-GBA ports that are in a better position to be fixed than Phantasia. Mother 2 for instance has a lot of potential in the future, a fan translation is in the works currently and someone was even looking to see if the palette could be fixed. The sound in Mother 2 GBA is also very messy but should be similarly fixable. Other than that the port seems decent and at least salvageable (unlike Phantasia).