Just too bad it's so short.. I've just been through it a few times and unlocked 4 cut scenes (one per play through), one triggers after the 15 minute time limit, and the other 3 you get when you exit to one of three other possible areas, but it'll end the demo after the cut scene regardless of time. Overall I had a blast with the demo and can't wait for the full game.
A few other cool things I found worth checking out, like:
- The lady with the trolley which you can grab and start mowing everyone down
- One of the cafés on the upper floor (I think?) has a stove... you can check it but I'm not sure if you're able to cook
- The bookstore with ability upgrades.