The intro was superb. Brilliant stuff. The rest of the level felt very promising for a demo, but a bit more unfinished than I expected from the screenshots and all. You've spoiled things a bit by posting too many screenshots, maybe
And using old tilesets a bit too frequently... I hope the finished version will have a story, some dialogue, and more knytts walking here and there, populating the landscape
I haven't found any real problems. I didn't find any of the challenges particularly hard; although it may have been pure luck with the first creature before the run powerup. The tower screens (with the springs and other stuff, x1005 etc.) were a bit uncomfortable because of the many random water deaths, but otherwise OK.