Panorama or Panoramic Control often referred as a ‘hub’ is where you can represent the UI of the application on a lengthy horizontal canvas that extends beyond the device boundaries.
The scrollable UI of the Panorama allows for a unique visual experience associated with the overall feel of Windows Phone 7. And is often the entry point for many applications.
Which means you need to be more careful with the quality of your Panorama and the feel it leaves.
The best examples are always on the device. The People hub on the Start screen is implemented using a Panorama and so is the Music + Videos hub.