Here is the site’s mission statement (there is no “about” section):
To create products that people love to experience
One of our greatest challenges is imbuing our products with “spirit” and “magic.” This is easier said than done. Designers at Microsoft work side by side with the world’s best software developers and usability experts to attain that elusive yet worthwhile goal. We take what can be a very complex problem and provide product design solutions based on a thorough understanding of the user’s abilities, hopes, and expectations. Through our design, we strive to creative products of simplicity that you will also find intuitive to use. We aspire to creative beautiful experiences that not only look amazing, but also make our customers feel amazing about themselves.
Like love, great design requires no explanation.
They then go on doing exactly that.