Here's a clip via Pure Nintendo that showcases some of the new features on Super Mario 3D World. It's informational, but also contains a few spoilers about the world itself, so view at your own risk. A few of the (spoiler-free) highlights:
You can interact with stages using the touchscreen and microphone
One of the worlds involves an old-school shooter style of gameplay
There's an unlockable bonus game and 5th character
That's all we can say without giving away too much! Spoilers or not, it looks fun. We can't wait to play.