The Windows Phone 7 UI is based on a design that is internally known in Microsoft as Metro, and draws upon the visual language of airport and metro system signage in its design and typeface.

Metros ideals of a clear, straightforward design not only makes an application legible, it also encourages usage and can lead to delight.
The Metro Design was developed using the five following principles:

1. Clean, light, open, and fast: distinctive usage of whitespace and topography to enhance the product
2. Content, not chrome: more of what interests you rather than borders, buttons and gizmos
3. Integrated hardware and software: Hardware and software working in unison to create seamless UIs
4. World-class motion: Multi-Touch and gesture experiences on phone screens are consistent with Windows 7 on the desktop. Hardware assisted animations to produce smooth and responsive user experiences
5. Soulful and alive: Automatically updating with relevant content and bringing to life a cinematic photo and video experience

Working from the Windows 7 Design Philosophy statement Solvd application design utilising Metro styled elements create a more consistent and fluid overall UI experience for users. 

Usability and design are the primary goal of app design and every Windows 7 app is designed with this at the forefront of our mind.

Solvd designers will discuss the design issues and constraints with you before developing use cases and wire frames. These become page mock-ups and we demonstrate how the design interacts with the inbuilt Themes system so that you are happy with the final flow and design prior to any code being developed.

The recent selection by Nokia of the Windows 7 Phone OS as the operating system of choice for their new handsets is likely to make an impact on both the Apple iOS and Google Android system alternatives.