There never should have been a demo imo.
The full game's opening prologue is pure joy, and introduces you to the core elements gently, succinctly, while working them smartly and seamlessly into a fantastic introductory level. The demo just kind of throws a bunch of bewildering toys at your feet and says "Here you fucking go then." I think it did more bad than good in attempting to entice fence-sitters.
I was lucky enough to play the full game in its entirety before ever trying the demo, and I'm glad I did.
pretty much, if there was ever a game where a demo hurt more then helped, its this one.