My daughters interview last year was with a Marine Reserve Officer who is an Academy graduate. He came to our home in Civies and was very laid back. My wife and I were ready to leave but he encouraged us to stick around. We kept out of the conversation, but it was a very easy interview, from my viewpoint.
This year, daughter was away at Northwestern Prep, so I called the BGO (same one) and arranged a phone interview. She called him at home and said it was really easy, he just wanted her to update what she'd been doing to improve her chances.
As an aside, our daughter has been talking to the officer in charge of Idaho BGOs (area coordinator?) for several years. He saw us last Thursday and complimented her on how much her SAT scores and application had improved, so I'm pretty sure they have access to the file.