It's exactly identical to this [1], which is quite good also!
I think the most important feature we have is that we remove about 80% of results from listings because they're totally redundant.
We also have draggable time sliders, instant sorting, and multiple searches in tabs, all of which are things we added to make finding flights less tedious.
Also, you can't book tickets on matrix...
Find a way to get Southwest in your output and I'll never use another site.
The hipmunk version actually has a ranking and crowding function, whereas matrix just lists them all.