[tathagata]

You can get the old interface by appending /?details=1 at the end of the photostream url. e.g. - http://www.flickr.com/photos/tathagatac/?details=1

[jarek]

But not by default, and not the previous "big photos in one column" layout for first page of photostream. (There's even a leftover link to change the layout at the bottom one's own details=1 page that 404s...)