I'm installing it right now, one awesome thing was when you were about to install it, there was a 'View Details' button which loaded up a page from playstation.com I'm assuming with the changelog. It only said one thing 'System software stability during use of some features has been improved.' but I can see how helpful this can be in the future.

If I notice any changes I'll post them, but I can only imagine that it fixes game crashes and just general stuff that isn't working properly.