I just had it this morning.
It was good. I looked at it as an opportunity to learn more about the strengths/weaknesses of my work, and to practice interviewing.
There were very few questions. I was told about the program. I got to explain the rationale behind my work, and why I made certain stylistic choices, and the rest was a crit. I spent most of the interview listening and asking questions for clarification, and at times (once or twice - it was a very insightful crit - explaining why I felt differently).
It was relaxed, informal and an education in and of itself.
I was told that there were about 100 people invited to interview for it, so I expect there are several profs doing this and no two interviews would be alike.
Advice? I don't know, I guess, try to be as relaxed as you can, don't be afraid to sell yourself a little as a viable candidate, and take it as it comes.
Good luck!