PCO is open-file.To start you'll have a quick file review with an admission staff member to go over your grades, ensure you have all your prereq's (or you're in the process of getting them) and let you know about anything that is missing. The interview takes place after, with another staff member or professor, one-on-one. Open file but very laid-back, felt much more like a conversation (which you are able to influence and steer towards topics you want to discuss).
I interview at SUNY on September 24th. This is a group interview - definitely has an intimidating vibe, and is open-file. I understand why people say there seems to be a focus on bringing up your applications weaknesses (any bad grades) but they really are just trying to understand the things about you that may not come across on paper well, IMO. If you see it this way, instead of as them trying to tear you down, you'll do well. And if everyone interview that day is acceptable they will let you - this happened will on my interview day and was an awesome end to the day.
Check out the interview section on SDN, has specific questions listen - VERY helpful for prepping!