Very informal, and incredibly responsive. You feel at ease with the interviewer, and it really did seem like you were holding a normal conversation with someone you just met. No trick questions, no "what-if" scenarios.
Be ready to spend about an hour to an hour and half in the conference room. You may lose attention since you'll be facing the window that has gorgeous views of Seattle. The views alone are worth the interview, because lets be honest... what better things do you have to do when you're unemployed?