It was open-file and very conversational. Day starts out with a summary of the school, curriculum, financial aid etc etc and then when it is time for your interview you go while others wait in the room snacking and chatting with current students. There was a student tour right after. I think it lasted till about 12pm or so but we got there early. They had multiple interviewers but for each student, it was one on one and seemed to last about 30 mins. Fantastic faculty and atmosphere. Not sure if this is the norm but I heard back one week later, my interviewer called himself.