This video shows you how you customise the UI with Windows Phone 7.

Luke Wroblewski has does a really nice blog and video to explain the concepts behind the Windows Phone 7 UI. He pretty much sums up the UI is a combination of “Teasing” and “Transitions” so the user can easily discover new information and does not get lost when transitioning between screen.

See his blog post here http://www.lukew.com/ff/entry.asp?1003

Check out the demo of Windows Phone 7 right now at http://windowsphone7series.com