What problem does it solve ? is it XSLT for JSON ?
I don't see it solving one problem so much as lots of them. With a decoupled front-end you can make applications which are much more flexible for dealing with change. Imagine swapping out the entire backend application, or completely re-writing the front-end - you can easily do either since the integration between the two is formalised and documented by the json contracts. That also means a new front-end developer ca…
In terms of a concrete example of what we actually use it for, http://www.nature.com/srep/ is using Shunter, as is http://www.nature.com/search?journal=srep&q=physics&subject=. Behind the scenes they're completely different apps, but they use the same implementation of the visual language so there's a consistent UI.