The general ideas behind it are very cool.
For example, when you're in tablet mode, everything goes full screen - but it's not just modern / store apps. It's desktop applications too. They're all treated the same by the UI now in tablet mode, including using the existing Windows 8/8.1 gestures to snap things to the left or right side of the screen, resizing them with a shared gutter, and closing them with a swipe-down gesture.
For example, when you're in tablet mode, everything goes full screen - but it's not just modern / store apps. It's desktop applications too. They're all treated the same by the UI now in tablet mode, including using the existing Windows 8/8.1 gestures to snap things to the left or right side of the screen, resizing them with a shared gutter, and closing them with a swipe-down gesture.