I attended the interview day 2 weeks ago. I really enjoyed it. There were at least a dozen MPH and MHSA students thought the day to answer questions and talk about the school. Everyone was extreme nice and engaging. It was a great atmosphere. I honestly wasn't seriously considering Michigan before the interview but the visit day had me considering leaving my deposit.
There was a faculty interview as well. It was a good opportunity for me to address any flaws in my application. I don't believe I would have gotten in without attending the interview day.
I received my acceptance about a week after the interview day.
Thanks for the feedback and congrats!