It definitely has flaws. A lot of them. But this game was the first to establish the franchise signature epic story and was very ambitious for its time. People rag on the skill system, but it's what ES uses. Just too exploitable.

the first warning sign that titles could lie to you

Square's always been willing to try out experimental mechanics in their RPGs. Here, sadly, that resulted in a game where the most efficient training method is to have your characters stand around in front of a wimpy enemy and whack each other in the head for hours on end. The later ports generally make leveling and combat faster and easier, but still....

The lvl system is good in theory, but it's ultimately unbalanced and tedious to grind for. The plot seems interesting on the surface and has some cool moments, but the characters are incredibly flat and uninteresting. The dungeon design is also awful - Way too many empty rooms and pointless areas. For what it's worth the game did come up with a lot of neat trends that would be utilized in future FF games, but this game on its own merits isn't good.

The weird one, with a bizarre and overcomplicated battle system that I have to admit to this day I still don't entirely understand. I give it credit for basically introducing plot to the Final Fantasy series, but I'm not a huge fan; it's the only one of the first seven mainline Final Fantasy games I've never completed to the end credits.