I'm a fourth year student at IU currently. I've also partaken in the interview day with prospective students.
The interview is relatively benign...though given the massive size of the med center, it may vary depending on who you are exposed to. For example, when I was applying, others had told me that they were asked questions about current events....at my interview, we talked about baseball.
Generally, you will be interviewed by two people at the same time...most are considerate enough to know a good deal about you before you get there, but that isn't always the case. The rest of the day will be filled with meeting current students and touring the facilities. Unfortunately, most of the students you'll meet are 1st and 2nd years...so they spend most of the time bitching about how hard anatomy is...and do not know much about the clinical experiences. I would focus more attention on the 3rd and 4th years students if you get the chance to.
Are you in-state? That makes a difference in the formal interview...they like to know why you chose Indiana.
Overall, I've been very happy with Indiana. I chose this school over others mainly because I'm in-state and the tuition was attractive. However, being at the end of the process...I think my exposure here has been phenomenal. Given the sheer size of the school...you get clinical experience in wide array of settings (county hosp, IU hosp, several private hosp, state mental hosp, VA hosp, separate children's hosp...etc). You do not find this everywhere. IU matches a lot of grads into very competitive residency programs in competitive specialties. On the interview trail, I've found a lot of other students at other schools do not get quite a broad experience as I got here. The IU faculty love to teach, and you'll get plenty of hands on.
Best wishes...you can PM me if you have any specific questions...
