I wanted to see how it worked, here's my thought process:

  * How does this work?
  * Hmm, no, I don't want to login or signup.
  * Oh, there's a small demo button.
  * Hmmm, I have to sign in?
  * *Sigh*, okay. Click.
  * Hmmm, a login page, this is too much trouble.
  * Leave.

Granted I wasn't too invested in the product but I recall there was one site (that "high-res" mockups one) that got promoted here recently that allowed me to start playing right away without signing in/creating an account.

Obviously this needs to be balanced against people who might build something and then lose it if they don't realise they have to sign-up to save it.

The provisioning and layout stuff is fancy. Nice work.

It would be good if they can go into the demo and then sign up afterwards and keep the site they created in the demo.

Also, it would be great to see a list of add-ons