For me... personally, the logo doesn't work.
I am slightly colour blind.
The logo in the article I see just fine, and all of the squares are the same size. And I get it... Metro theme.
The favicon.ico and small logo on Microsoft.com
Those don't fair as well. The red and yellow squares are much larger than the green and blue, and my eyes see a throbbing line around the bottom and left of the red box, and a black line at the bottom of the blue box.
Now... I know that those boxes don't have those lines. For I know what the Metro style guide looks like. But there it is, the logo has not been viewed by anyone colour blind with the ability to have it modified. There should be more space between the boxes when it's shrunk.
The red box is literally 20% wider than the blue to my eyes.
You know how much of the population is colour blind? A very significant chunk.
Also... those colours... very bad choice. When you print this logo (greyscale), all of the colours come out too similar a shade of grey. There is no distinction between them.