The demo is fantastic. You took everything good from the tech demo and enhanced them, as well as adding a bunch of new cool things. This series is pretty much all I want in the way of new games this year.
I could see the improvements from the tech demo right away... truly amazing, especially for an indy game. The hammer did feel odd, and phrases like "Hopefully, I can still examine things with right click." really broke the immersion, but these are just minor quibbles. The demo felt way too short, though. More download time than playing time.