A bit late, but...
Curriously, I've always felt SD2 was one of the most, if not the most, overrated game of the SFC.
Maybe due to its ugly French translation.
It's probably because it was one of the first "big" action-RPG that got localized in french.
I personally think it's the third that is the most overrated, and one of the main reason, in my opinion, is because it was only released in english as a fan translation (the fact that it was probably one of the harder game to hack, back in those days, because of huffman compression, is not enough to just make it a awesome game, though I suppose and can understand that lot of people were like "woot, WE CAN FINALLY PLAY IT IN ENGLISH, THIS IS THE BEST GAME EVER !!").
I'm not saying it don't look like a good game. I just know that I really like SD1 (Mystic Quest) and SD2 (Secret of Mana) but I never really managed to like as much SD3, though the several scenarios divergence and such was a pretty good idea.
The original french translation of SD2 is not that bad for a 1993 translation (I can confirm it as I read the official japanese script when I did my copy-paste from the retranslated iphone version to the snes rom), it's just heavily cut to fit in the 16Mb rom. I would say half of the text has been cut, but in a so tiny free room for texts, the translation look rather good, especially when you know the english localization seems to only got one month to do it and when you know the french version, is of course, translated from the english version (I think the first big RPG directly translated from japanese we got in France was FF8, after FF7 translation debacle).