GUI install of (null). Created root's password. Created new user and gave it a password. Created second new user and gave it a five-character password. Whilst typing it in the first time, it told me it was too short. Whilst typing it in the second time, it told me it was too short. Clicked 'okay'. It didn't give me any feedback about whether it has created this second account with the dodgy password or not. I'm none too sure whether I shall find this second user account actually exists now.
Oops, I lied on testers-list... they were being added. That's fixed now. Still want to get notification (or at least leave the dialog up) if you can't add the user for some reason
We've removing the option to addusers in this screen for future releases. It will be handled by firstboot instead.