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.
Also see: <a href="https://news.ycombinator.com/item?id=10532957" rel="nofollow">https://news.ycombinator.com/item?id=10532957</a> for broader discussion