Ben Thompson wonders (as I think we all are) why would Microsoft do this deal now when they already essentially have everything they would want from Nokia:
I theorize that Nokia was either going to switch to Android or was on the verge of going bankrupt. (I suspect the latter: part of the deal included €1.5 billion in financing available to Nokia immediately, and the fact Microsoft had to take Asha but not the brand or maps suggests they were trying to keep the price as low as possible). And, had Nokia abandoned Windows Phone, then Windows Phone would be dead.
The loan aspect of this deal is very interesting and seems to say a lot. Exactly in line with my thinking in June.