> Why is there a giant search bar at the top of the screen?

This will be (if it isn't already) integrated with their search product. In other words, it'll be a part of search. You'll search for "flight from ny to sf" and that's what you'll see. Perfectly natural for them to have a consistent UI in their search product.

> Why is there a giant map at the top of the screen?

It's interactive. Try pulling the marker from one location to another. Very cool. I can also see the exact route that the flight will take. More intuitive.

I may have a general area of where I want to end up, but this lets you choose exactly where through a visual map. Again, very cool.