This depends largely on the users expectations.
If the product is presented as ready to go and the user starts finding bugs right away, you could be in trouble. In my experience it's often the case that sales people will want to go out and suggest that your product is slightly further along that it actually is in order to maximize sales; it's going to be easier to sell something that's ready today than something that's just a pipe-dream.
If the product is presented as a work in progress from the outset, then bugs will not damage the reputation. The user is already primed to be using their imagination. When they find a bug they can overlook it because they expect them to be ironed out in future as part of the natural process that's on going, what's important to them is a demonstration of potential value once development is finished.
The site you've linked to doesn't seem to make it clear on the homepage that the product is in active development and is pre-release. Therefore, I would say that bugs showing up within a few minutes of use in the demo will potentially harm reputation.