Price. I bought a Nokia Lumia 710 just to try it - it was 205 Euro. For that I get a phone that feels fast and runs the now-current version of Windows Phone. In the UK you can buy a Lumia 710 with a prepaid SIM for 99 pounds. At the same price level I get a Samsung Galaxy Mini 2 with Android 2.3 (an operating system from 2010).

tl;dr, Thanks to good software engineering and lower specs, you get a phone that is completely up-to-date software wise at a great price point.

http://www.intomobile.com/2012/06/04/uk-nokia-lumia-710-now-...