I think every RPG is too short, but then again I play most 24/7 when I get them -- including KH2. =\

Edit: Leveling up, level Drive forms, get final weapons, beat Sephiroth, get 100% in Jiminy's Journal clocked me 40 hours on the game all up (including the actual story). But I haven't tried the Gummi Ship missions. So it's still pretty short.