I love this game mainly because the storyline was complex and interesting and better than some storylines we see in RPGs today (although it was, at parts, a little confusing). The characters were awesome too, and each got plenty of development (even the "secret" characters, Vincent and Yuffie). The whole love-triangle thing was good too, as it was left up to the player to decide who Cloud really loved.

So yeah, that's why I like this game.