Actually Paul Thurrott thinks that the Finnish smartphone manufacture has a number of advantages, but the biggest one in his mind is simple. Colour (or color to our North American friends).

Moving away from the unibody casings of the Lumia 800 and 900 to the customisable cases of handsets like the Lumia 820, 620, and 520 is about many things, and not just the look of the machine:

This customization ability isn’t just about fashion. It allows Nokia to sell the devices more cheaply and then integrate additional functionality, like wireless charging, into the separate back plates, each of which is available in different colors. Presumably they could also offer separate back shells without this functionality as well. And let’s not forget that these designs have user-replaceable batteries, so road warriors can pack an extra battery while away from home.

This design makes an otherwise pedestrian device like the Lumia 820 suddenly very compelling. And Nokia has taken this design to a new level with the Lumia 620, which offers “double shot” shells that blend two colors together—like yellow and green or yellow and red—in very attractive ways. So far, this is unique to the 620, but it really makes a low-end, small phone a heck of a lot more fun.

Thurrott has said he'll be going into more reasons to choose Nokia over other WP handsets in the near future. I suspect 'camera' and 'maps' will be on that last, but for the moment, all his thoughts on the colours of Nokia can be found on his 'Supersite'.