In general, bringing an app from the web or another platform to Windows Phone requires app screens to present fewer controls and graphics and cut clutter.
It also may be necessary to distribute tasks throughout several screens in a taxonomy that makes sense, whereas on the web, controls are more likely to be nestled together in large groups.
Be sure you’re aware of whether you need to scale up graphics, content, or photographs that your app will feature.
Be sure to prototype with native controls, and as few WebBrowser controls as possible.