I had an interview with four people (one at a time), all creatives (this after an initial phone interview with HR). Two were Art Directors, two were copywriters. They mostly let me talk and explain my portfolio. They really liked that I brought a print version of my portfolio and a copy of my resume for them to take with them after the interview. It's very intense, because I got about 40 minutes with each person, so after 4 people I was exhausted.