My feeling is that slowly but surely, the travel sellers who buying leads from Kayak will start paying less. So while I see it as a successful business, I'm not really sure where they're planning to go from here.
Someone from there (CEO? CTO) has posted on hn and/or quora and seemed really smart, too. Obviously they're in quiet period now so won't be commenting.
They seem pretty flight-optimized, at least for me, which is a much lower source of revenue than hotels. If they can grow their standalone hotel res business, or add hotels to flight purchases, they'll be worth a lot more than even being totally successful on flights. (I book all my hotels direct with starwood or with the property on negotiated rates, though, or use airbnb or a few specialty negotiated-rate networks like Tablet).