Either that app is really good, or the demo video was really good.

I normally don't get excited over tools like these, but wow that actually seemed very well done and very impressive.

The HTML/CSS code it produced was beautifully clean, so interestingly I'm actually most excited about the possibility of this being used as a training tool: the option to be able to instantaneously see the code in a side window as you're 'drawing' it -- this kind of simultaneous feedback is always a real boon for the beginner learner.