In general, I'd found the BCG events I'd attended to be quite well organized and professional. This did not apply to my interview experience, however. To start things off, the interview scheduling was a giant mess and I walked in on interview day just praying that the final of the multiple times I'd been given was actually correct.
On interview day, I had an observer that was collecting feedback on my interviewer. That was fine, however, she typed during the whole interview. So I heard the clickety-clack of her keyboard throughout the entire thing. It seriously sounded like one of those old IBM keyboards. The professional way to approach this would be to have her take paper notes or just record instead.
One of the two interviewers was really good. The other seemed like he was not at all prepared to conduct an interview. It was like he was waiting for the questions to just come to him throughout the interview.