They were very professional and well prepared, but that was the most demanding, time consuming set of interviews I've ever gone through. After answering a few questions over email and the initial phone screen, they provided me with a mockup and specs to build a small application. That took more than a couple hours to complete. Then the office interview lasted about 4 hours and involved a couple simple whiteboard code tests (css and my choice of programming language), a small design challenge, and a lot of in-depth, on the spot, "tell us about a time when" questions with different departments. They were courteous enough to provide lunch part way through, but after all that I almost feel like I should have been paid for my time.