Having worked at the University of Iowa's ED in the past I can tell you what I know...........pretty low volume (I belive around 30-35,000) visits per year. Due to this they rotate you up in Cedar rapids for several months during your residency which sees about 55,000/year.
Nice new ED in the works. Iowa City is a very friendly, small town (60,000). Virtually no knife/gun club. Little trauma and what there is is mostly blunt from MVC's construction. Iowa is a Level 1 trauma center and gets flights from minnesota, illinois central/eastern iowa and northern missour. So you do get some cool traumas, but pretty few and far between from what I remember.
My personal concern is the volume. It's just not that busy of a place yet.
Otherwise, Iowa City is great and the rest of the hospital is home to amazing medicine.....Sometimes we'd get Mayo's helicopter bringing us patients. I'm not for sure how the ED residents are viewed around there.