Amongst the changes is a new tab which shows reviews posted by the user for local establishments. This ties into a push by Google to create more contextual content like reviews and prices to feed into its search engine and ad business. The reviews tab can be hidden from public in the user settings, or shared using the '+1' mechanism (similar to a Facebook like).
The most noticible change is the larger covers photos (now up to up to 2,120 pixels by 1,192 px). This addition forces the profile content down by a few hundred pixels, which seems to me to be a waste of screen realestate and a game of 1-upmanship with Facebook. It looks attractive though and the 16:9 aspect ratio means a wider range of photos can be used without awkward cropping.
The new features were announced quite appropriately on Google product manager Sarah McKinley's own Google+ page. This announcement preempts the profile design changes Facebook is expected to announce tomorrow.