While the capabilities of the open-ended design of the search is amazing, when I search for flights, I find that I am looking for something very specific. I know cites and dates, direct flights only. Even before getting married and having a kid, I generally think about where and when I want to travel well before I start searching online. I don't know if other people are more spontaneous than I am, but I am constrained by PTO days, other people's schedules, etc. At the most I want the flexibility to change the leave/return dates by a day or two.
Since I already know the parameters of my trip, I find that the input that most travel sites have settled on (To, From, Include nearby airports, Leave date, Return date) gets me to what I'm looking for faster. The open-endedness of the Adioso search box was actually slower, since I tended to type too little and did a lot of filtering afterwards. It felt like my choices are either I type too much and the computer doesn't understand, or I type too little and "fix it myself".
From my biased perspective, I think it would be a big win to have the traditional search inputs be the default but with the open-ended search as an alternative input (not "Advanced search" but maybe the link is "I'm flexible"). As an alternative search, it's no longer a limiting search but it now feels like: you can type anything and the computer just figures it out! Sweet! Also, user education no longer is a problem- everyone knows what to do with an "I'm flexible" search box.
The other big speed advantage of the traditional search input is: often I will return to a travel site weeks later and my trip details are already pre-filled and all I need to do is hit the search button. You can't really do that with a search box. (When I hit back from the Adioso search results page, I lose everything and the search box is empty. That seems like a bug, I think I should be able to save at least that little bit of typing.)
BTW, I didn't feel like Adioso search (getting back the initial results) was slow at all. It felt just as fast as any other travel site and definitely faster than the worst of them that leave you staring at airplane animations for 10s of seconds.
Great work, I'm really interested to see what happens with Adioso. I'll definitely be trying it more in the future!