Its like this- Normal is easy, you practically go threw the game without any worries and never get stuck. If you do, you dont need to do much to win.
Expert- Annoying like hell. I nearly gave up on Wonderland. :dry: I couldnt beat Clayton and had to go back to Traverse Town and level up 10 levels just to continue. The end bosses for every world is hard, and Ursala is practically invincible. I beat her first form after a while, but the second form was too hard and i had to swim as far away from her as i could so Donald And Goofy could beat her. Getting stuck on bosses is common from there on, and Sephiroth is probably practically invincible until your on the highest levels. :)