Sorry, folks - the upgrade was to 28.0.1750.51
It looks like it is aimed at tablets, smartphones etc, and not for a boring old PC.
To Leocg - I can change the theme to one of the limited pre-loaded versions, but there does not seem to be an option to link to anywhere else for other choices.
I think I will now uninstall it, and wait for v12.(x+n) where x and n are integers.
Thanks for your feedback!