There may have been some issues over the weekend - but booking this morning it all worked.
For the first time I have also had my credit card details pre populated (only needed to key in the verification code).
What didn't work is that on the personal details screen on the booking, I wasn't able to edit anything.
In my case I wanted to change the nationality as for some reason it did not pull that from my profile and instead listed my nationality as Singapore (where I live). The pull down menu did not work.
The confirmation email now also has a new look for me.