Really it's the sixth in the series. This is the best 2D Final Fantasy game out there.
Something that makes any game is a good story. No matter how bad or outdated the graphics are, a good story can make or break a game. This has to be one of the best story lines every written for a game, hands down. I put this right up there with Chrono Trigger, which is number one on my list.
Bottom line is, if you don't have a SNES, buy one off of eBay and get this game... PRONTO!