Initial interview on the phone - 4 people on the call. Lasted about 45 minutes, I believe. Second interview was a "panel interview" lasting two hours - one with peers (6 people I'd be working with directly), one with the management team (3 people). Peers went first. They each took turns asking questions, and after I answered each one, they wrote notes down. They left, and the management team came in and did the same. It wasn't a bad or necessarily intimidating process. I enjoyed the people I interviewed with. But you should definitely eat beforehand, and maybe bring a bottle of water with you. My interview was first thing in the morning, and I kind of faded in the second hour.