The Google+ lightbox was already nice, but it has been imp-roved. The lightbox is the area you go into when you click on and are viewing a photos. Google’s lightbox is black, and there are a lot of folk who prefer that (eg Lightroom users) and others that hate it. In theory the black borders will give photos a “lift ( according to the block border enthusiasts it apparently boos the intensity of colours and the luminosity of the light, I think these is an optical illusions in the viewer). The problem them in things written in the black boarder can be very hard to read, so google+ has white boxes into which comments etc are placed. It is a nice slick update and very simple to pick up and use.
Have fun tagging your christmas snaps or adding santa hats and antlers (watch the video carefull and you will see how to do that)