Backend is C++. Means it's easier to integrate with existing applications. Looks easier than Caffe. I can't use Theano because I need to be able to compile to a native application.
It may interest you that William Kahan has written quite extensively on the pitfalls of iterative algorithms on floating point numbers; his discussion of Muller's pathological recurrence on pp. 14+ of this
paper seems particularly relevant.
It's good to see Microsoft investing time and resource to recognize community contributions. They should open similar platforms for Mobile, Azure, SQL and Windows Developers too. www.windowsclient.net used to be a good resource for Windows App programmers, but it's been abandoned
equinox put it very well - My interpretation of things: Since Nokia is now (or starting next week) a Windows 7 outfit, we're no longer investing resources in this. So, we'll make it open source and hope that the community will sustain it. This is sad.