Personally, i thought the storyline was pretty crap. The only time i found my lower jaw detatched from my upper was when you find out that Yevon are a load of dead men who want to destroy the world and betray their own teachings.
And some people's involvement in the story was nil. eg wakka and lulu.
(Warning spoilers ahead.)
Unlike other games where everyone had their own mini-adventure so to speak. Take FF9,
Zidane wants to find out what his relationship with Kuja is,
Dagger wants to find out who her real mother is and stop kuja from taking advantage of Brahne.
Vivi wants to know who he is and where he came from.
Steiner wants to protect the princess and finds himself betraying his queen.
Freya returns to her homeland to protect her king after deciding not to return. (also her love with sir fratley)
Eiko fancies Zidane and finds dagger as another summoner but without no horn.
The others i'll give, but i hope you see what i mean.