Back to the topic at hand shall we?
VII is a great game and overrated yes, however every single Final Fantasy is Over rated in its own way... well ok maybe not FF1 but thats a grind fest of a game (And I loved it) ... anyway it really is going to boil down to who you are talking to.
For me VII is overrated now I say this even though it was my first Final Fantasy and I love the game and the battle system was great! However it has alot more hype then it earned over the years cuz of the fanboys.
Hell even VI is overrated in its own way (I feel like I am going to die for saying that here) and even IV is overrated and that is my favorite of all time by far.
Sure this is a topic of what one we think is the most overrated and I am looking forward to seeing everyones answers so ill say up front what I think is the most overrated and then i will nit pick at all the other games of what i think is overrated about them.
VII is the most overrated cuz of the fanboys, good game, decent story, not the best game ever like most want me to believe.

IV i think in its own right is overrated, more so if by SE then anyone, as I do believe it has more remakes then any other FF now (I own them all too...) The story all be it good has alot of lacking elements imo.

VI is a great game i am saying that now so some people I know wont drive to my house and stab me in the night dressed up like Kefka... *Cough* WolfKanno *Cough* While it is a great game it suffers from the same thing that all great games do, Fanboys, now I am a very picky person so feel free to disagree with me but I think the Story is lacking in this one on some elements as well, now i cant say much more about it sure but it sure the heck is not the best game of all time imo just like 7 isnt.

VIII another great game but overrated, I feel the battle system is half assed in this one... cuz well it is... also the story near the end just makes me want to stab something cute....

IX was hit hard by 7 and 8 fanboys for not being as good imo really, that said they just dont know how to deal with a medieval FF if they only play 7 and 8, however the way you learn abilities was crap imo and some of the chars where lacking.

X .... well really the story was the biggest hit on this one, chopping writing imo.

XII Im not even going to start on this one but that is a personal reason that I do not wish to spend time on this game, good game to some, but not to me.

XIII Story...

Now like I said I am picky and I to nit pick at flaws but in a argument with a fanboy that thinks something is perfect, flaws are what you have to point out thus I feel that they are the argument to overrated as well, now I did say story in alot of those but mainly just some of the elements of the story, now then I think I have gone on long enough.