Windows Phone 7, coupled with a popular and trusted brand (Nokia) is a potent mix.Over 90M phones sold in ONE quarter by Nokia.
Now there is a billion and a half desktop computers out in the world. Apple has claimed to have 200M iTunes accounts with compatibility to Windows PC's. Yet, iTunes is FREE. Some Nokia phones were not given away for free and it sold 90M in one quarter while iTunes has been around for ten years. Many popular YouTube videos don't get that many views at 90M and certainly not in just a few months. I can imagine many companies can't even match that number trying to sell chocolate bars for 99 cents. Many songs at 99 cents or less will never be downloaded that much. Angry Birds hasn't even come close to selling 90M. Over 90M sold and it is a considered a down year for Nokia. Seems like over 90M people last quarter don't give a rat's ass about an ecosystem.
I am comparing phone sales from a particular manufacturer that aren't always given away for 99 cents or free to things that are either 99 cents or free. Sometimes we say it's a small world, but sometimes we realize there is a much bigger world out there. This is why Windows Phone will be the #2 most popular mobile OS globally by 2013 considering Symbian still outsells Android as of today. Most of the reason is because of Nokia's own brand power and not really because Microsoft created the best mobile OS in the world.
Not that I'm saying HTC, Samsung and Dell (current WP7 manufacturers) are bad but they are still not as a popular as Nokia.