It may wind up serving a different consumer space than the Android or iPhone app-heavy consumer, and that's why it's interesting.
This is why I was really hoping that the rumors about MS buying out Nokia were true, that would get them great hardware to go with great software, then they could really push again this holiday. For all Zune's hardware problems in the beginning, the Zune HD was really a nice piece of kit, as is the Xbox 360. Microsoft does know how to make great consumer hardware when it wants to, people just forget that they do.
If so, that may have forced Microsoft's hand in their completely different UI.
I guess you'd say that even if you were forced down that route, but it's still interesting to see good design and different thinking coming out of Redmond.
And icon based UI has been around a long time. http://img.zdnet.com/techDirectory/_PROGMAN.GIF
Apple and google(they bought the company Android) spent a lot of time designing their mobile OSes.
MS would have to spend the same time designing the UI, they do not have time, so they created something very simple(drawing simple vector shapes with orthogonal pictures is extremely easy and fast to do), and will use money to force their product into the market, buying whatever they need(just Nokia deal took MS BILLIONS vs Android taking tens of millions from Google, add the money they will give to carriers) because they CAN'T LOOSE THE MOBILE WARS. If they do they loose the train of the future.
Don't mistake a lack of "flashiness" for a lack of taste. Windows Phone is a pretty classy product with a decent chance of success as long as Microsoft doesn't shoot themselves in the foot.