i thought i got a horrible interviewee. He/she asked me actual questions that were pretty hard, and some of them i didn't know the answers to, so i felt like i gave a crappy answer. Other people got interviewees which were more laid back and conversational. So i thought i didn't do too great, but i got in on dec 1. it was a big surprise so i guess i didn't do that bad on my interview after all.
also, for the student interview, you should take it seriously since They evaluate u just as much as ur faculty interview.
good luck on ur ucsf interview!!! when is it btw?