If you click on You and then Photostream, your photos appear in the wall-to-wall mosaic. Click on Edit and you are back in the old familiar view. It also loads just one page at a time, which is so much better for speedy access, especially if you want to jump back a few weeks.
I had seen the Edit option, but assumed that it took you to a photoediting page, so I didn't try it, but fortunately one of my Flickr friends did and passed on the good news. :)