The best 2D Action-JRPG
I loved Secret of Mana already, as it was. And this game improved alot on it, with a better pace for the combat, character customization, giving you the ability to distribute your skill points as you wish, on whatever you want to focus.
But the main thing about this game is the fact that at the beginning of the game, you have a choice between 6 characters, and you have to pick 3 of them, one main character and two side-kicks. And each character has its origin, its hometown, its motivations. Telling a different story between each of them, depending on your choice. As well as the other characters you pick, changing dialogues and sequences throughout the whole game. But not only that, depending on the character you pick, the main villain changes! That's right. They did that in 1995! This game was so ahead of its time. Plus the fact that each character can go through 2 class changes during the game, giving you 2 options on the first go around, and 2 more on the second time, depending on the one you chose the first time. So that's 7 classes per character, the one you start, two derivations of that, on the first class change, and four more, two for each of the first two you chose between. With all of that, the game has so much replayability, you have tons of different perspectives on the story, plus different ways to distribute your skill points, and four different paths of class changes for each character.
Another thing that can't go without mention, is the soundtrack. Again, square kept the highest level of work for their scores on JRPGs, especially during that era. The game also looks really well, even better then his pre-quel.
You don't need to play Secret of Mana to play this game, it's just in the Mana series, having the same monster designs, the same type of lore and spells/UI/equipment. But Seiken Densetsu 3 is its own story, and you should play it, maybe more then once.
The only negative with the game is the delay you can have during battles when you need to use too much magic. And sometimes not having the opportunity to use it.