When the user views my lightly-modified checkout page, he sees "create or use account" selected as the default checkout option. Great, that's how I configured the client's store. When the user clicks the "checkout as as guest" radio, the "continue" button disappears. That makes sense, I guess, we're not calling up account info if he just wants to be a guest. But then if the user changes his mind and reselects the "create an account" radio, the "continue" doesn't reappear. This seems incongruous to me. Maybe I'm missing something, but It seems like the event of the "create an account" radio being checked should always show the "continue" button".
Furthermore, when the user goes ahead in this state, and enters an email address, the "continue" button still doesn't reappear. (Interestingly, if the email address he enters doesn't validate, then the "continue" button will reappear, along with the error message.) Seems odd.
I hope this is clear. Most of this store's users check out as guests, but I do get emails forwarded to me from time to time from users who get stalled somewhere in the checkout, and I'm usually baffled 'cause they're not detailed reports, and hence usually impossible to reproduce. Hopefully this is useful.
(BTW I love the address handling improvements in 1.0. Brilliant!)