Earlier quoted context omitted.
Erm, always killed it? Zune, Surface, Lumia?
IIRC, Surface is one of the key reasons Microsoft did so well in the last quarter.
I wouldn't say it's a key profit area for them yet, and we also can't call it a success yet (as they haven't reported the total retail purchases).
[1] http://blogs.wsj.com/digits/2014/10/24/a-win-for-microsofts-...