3 of 21Image
New Start theme setting
You can select different background images and then see many of your Live Tiles change to show parts of the image. It's pretty slick how scrolling up on the Start screen scrolls through the full image even if some of your Live Tiles don't show the theme image.
Application launcher clearly shows you new apps you installed
Setting up Action Center
Action Center is one of my favorite parts of the update and, unlike the failed iOS implementation, this one from Microsoft truly lets you take action on notifications and has deep support for applications.