Well, there is no such thing as a hard FF game. But compared to the others it was a bit more challenging. The problem with the other games that came out after it was that there was always one spell or super *limit break* that should you get, would completelly destroy the boss of the game in like one hit. It totally defeated the purpose of having a boss in the game.
I also thought FF3 was just so powerful and innovative for it's time. To have such beautifully developped characters on the SNES was indeed a rarity, only captures later by Chrono Trigger.
FF6 was the masterpiece of the series, I have always thoguht so ever since i first played it back in like 94 when it was released, and still now, i can go back and play through it and get completely engrossed in it's engaging and epic storyline.
I didn't have a problem with the reality aspect of it, i think it was a nice take on the fantasy thing. But it just felt really rushed (it came out very quickly after FF7) and the characters were all so one dimensional. I also didn't like how the villian wasn't introduced untill the end segment of the game.
The best part of FF8 was that awesome card game.