Do not misunderstand me, Final Fantasy VI is a veritable Good Game. The SNES version (known as Final Fantasy III) suffers from a myriad of issues, from localisation errors and mistranslations to extensive programming errors that render stats useless, moves unlearnable, effects unusable. While some of the issues are not unique to that version, as they are included in the SFC version, we're only talking about release outside of Japan.
The GBA version is far superior in most respects except in audio quality (which I believe there's fan-made patches for if you're running it on emulators). It is a shame that there's no "definitive" version of the game available for purchase.
As it stands the smart phone version has... issues, but the least of them are the graphical changes, which are mostly okay. The only real aesthetic issues are the blurs and filters applied to backgrounds and the 3D models not really fitting with the overworld. The new sprites are fine and stick to the artstyle the sprites were based of off (and I believe are actually made by Kazuko Shibuya, the same artist that originally drew the chibi illustrations and sprites). What's not really acceptable are the myriad of newly introduced typos that all the mobile versions added, which are ridiculous since they're reusing the scripts, implying they manually retyped in every piece of dialogue in the game. The game itself is fine, though, given its running the GBA ROM with a wrapper around it.
But I digress.
My point is, the SNES version isn't a "good" version either, so playing the SNES Classic doesn't get you that.