I beat Power of Illusion in 3 hours and 12 minutes. The demo is misleading because it gives you a lot of sidequests that are from later in the game, there are not that many that fast when you play it. There are only 11 stages and 3 bosses. Just Intro castle, London skies peter pan, neverland jungle peter pan, captain hook's ship peter pan, captain hook boss. Next castle stage, Agrabah Aladdin, Cave of Wonders Aladdin, Deeper Cave Aladdin, Jafar snake boss. Underwater Castle stage, Little Mermaid ocean stage, Eric's Castle Little Mermaid, then crappy locked room enemy gauntlet ripped straight from Henry Hatsworth before fighting Misrabel which is Maleficent Dragon. I'm spoiling everything to spare you. It sucks. Don't buy it.
Some spoiler tags might have been nice instead of telling people every single thing that happens in the game. Believe it or not, some people might actually want to buy it still.