When visiting the main site root, there is an error rather than a redirect to 'sign in or sign up'.
When you do find your way to the sign-up page, it's quite easy to pick an email address and a password, but:

• It seems there is no email verification?
• An account seems to have zero pods by default.
• Creating a pod asks you to give it a name.
• Creating a pod asks you whether you want to use your webid in the pod or an external one.
• When registration is finished you end up in your account settings, not a place where you can start using your pod.