The question I have is as to their business model.
There's a saying--- if you aren't buying a product, you are the product. So they have one paid link per page. Is that enough to make them profitable eventually?
I don't see why not. Their costs are probably minimal (some servers + salaries). Beyond that they're just leveraging all the work of Bing and others. Also, they've taken barely any VC money, so it's not like there's a huge return expected in the first place.