I'm getting a 400 error when I try to complete the 'choose a username' screen.
No visible reaction to pushing the continue button at all, but the error shows up in chrome's console.
"Uncaught SyntaxError: Unexpected token O"
Chrome 25 on windows 7.
I just tried again from scratch, without going through the google oAuth page, and its worked this way. No idea what went wrong the first time around.