To those who are expressing (understandable) anxiety over the interview, allow me to offer my perspective as a parent whose son attends Princeton. When he went on his interview, he felt it went fine, but nothing special. After he was accepted, he later met with the interviewer at a social gathering. The interviewer was happy and surprised because no one they had interviewed had ever been accepted. My son’s response was that this made sense about the perceived lack of excitement during the interview itself.
So, take that into account. The interview is just a piece of the puzzle. And the interviewer himself or herself is human and brings their own issues to the table (for good or bad). I would just say to relax, be yourself, and ask questions to determine if you would be happy at Princeton. It’s not all about persuading the interviewer about how great a candidate you are.