It was easy to remake Final Fantasies IV and V, because they weren't perfect to begin with. They had solid gameplay and weak scripts. All the designers had to do was write a competent translation and increase the game speed, and that alone made a big improvement.
But Final Fantasy VI is a different story. It is a landmark in RPGs, arguably the best one ever made. Unlike its predecessors, it was already perfect when it came out. It was fast-paced, it had a good gameplay system, a great dramatic storyline, and it even had a good script. Granted, Ted Woolsey made a few grammatical errors now and again, but think about it: how many translators are there whose names are remembered by gamers ten years after their last work? His writing at least had an individual style.
But it wasn't just the translation. Everything about Final Fantasy VI had an individual style. For example, the game used a dark, subdued colour scheme. Even the first overworld map used dark shades of green and blue. And this helped create a unique atmosphere. The town of Narshe, comprised of black rock and dusky-blue snow, was a minor masterpiece of set design by itself.
Unfortunately, the designers in charge of the remake didn't understand what made the game special. So, they treated it just like Final Fantasies IV and V. They rewrote the script, renamed the items and enemies, and increased the game speed. After all, it worked for the other two games! But it doesn't work here.
The changes serve to make this unique game look like a generic 2D RPG. For instance, they made the colours brighter, for no apparent reason. And that just makes everything look boring, less textured, less detailed. It's really not as petty an issue as it might sound. Final Fantasy VII also used a dark colour scheme to make the city of Midgar look big and dangerous. Had the colours of Midgar been this much brighter, it would have destroyed the dramatic effect.
The same goes for the new script. They did use Woolsey's translation as a guide, but they added a lot of unnecessary extra lines, and rewrote other lines that were perfectly good in the original. Usually, the rewritten versions are more bland. For example, Woolsey introduced the ninja Shadow by having Edgar say, "That's Shadow! He'd slit his mama's throat for a nickel!" Now, Edgar says, "That's Shadow! He'd kill his best friend for the right price!" which just doesn't have the same panache. Similarly, Kefka now yells "Son of a sandworm!" instead of the delightfully odd "Son of a submariner!" Adding extra humour to the script doesn't work either. It worked in Final Fantasy V, because the storyline of that game is so bland that it needs a few goofy jokes to sustain the player's interest. But this game's story can do that on its own merits.
The remake also messes up the pacing of the original. The cutscenes now move much faster than before, whereas battles are actually slower, and Mode 7 scenes (e.g. riding a chocobo) actually lag. But worst of all is the sound. It's flat and tinny, not just in a few spots, but everywhere. Again, this was fine in Final Fantasy V, because the music in that game was flat and tinny to begin with. But not in this game, which used the SNES hardware to its full extent, to play music that was so good and so suitable to the subject matter that it served to play a big dramatic role all by itself. The remake just proves that the GBA isn't as powerful as the hype made it out to be, after all.
The underlying gameplay is still great, of course, so the remake can't really be bad. But it's not good, either, not at all. Maybe the only good thing about it is the fact that it unintentionally proves how much a game can be affected by small things. Turn down the sound quality, increase the brightness and contrast, add more text, and there you go, the best RPG ever made becomes something much smaller and less interesting. Don't buy it.