The genesis version of UMK3 is actually WAY more accurate compared to the arcade version, if you can play anything, play that.
SNES has faster speed, which isn't always a bad thing but in this case it is. Animations use less frames which mean moves have different properties. Most characters recover faster from their moves. There are several broken infinite corner combos using knee lifts. The list goes on.
All of this makes it a completely different game much like the N64 version of MKT, and can't be taken seriously along with the standard games. You can be really good at using the broken tactics in the snes and n64 games and completely suck at the arcade games.
Is it fun? Sure!