it depends on the school. i interviewed at three schools last year and was not accepted to any of them (all waitlists). i was able to speak with the admissions deans at two of the schools and both told me that my interview was one of the strongest aspects of my application. in the end, however, that still wasn't good enough. i knew my grades weren't very competitive though. so, the whole spiel of 'once you're at the interview, you're on equal ground with everyone else' may be true at some schools but it doesn't seem that way at others. best of luck.