I haven't really had much time to mess around with this search engine, but it does seem pretty innovative. It doesn't have the answers to many questions I've asked it yet so they're probably still working on it.
I read an article on it a few months ago. Since then I have seen a couple of reviews.
The general conclusion seemed to be that it was an interesting idea, with potential. But that it was a bit of a waste of time at the moment.
The biggest advantage of it existing, though, is probably that it might make Google & Bing innovate their own search engines. Having said that, Google tried doing structured data search in Google Squared, found in its Labs section, & apparently made a mess of it!