I've been to 2 Cy-Hawk games at Kinnick and tailgated for a handful of others. I only had an issue in 2002, when a grown man was taunting me (a 12 year old at the time) when Iowa went up 24-7. When Seneca completed the comeback, I said "how bout them Hawks?" and he lunged at me. Luckily my friend's dad, an Iowa fan, sat him down real quick.
Their walmart fans are terrible, and their casual fans are extremely arrogant, but I've never felt threatened. They're mostly just Iowans who wear different colors. They do have more of a mean spiritedness to their taunting, where ISU fans are more chip-on-the-shoulder types. Not a great combo. I do think the rivalry has become more intense and angry with ISU getting better at football, the growth of Des Moines and ISU fans in the area, and social media showcasing the absolute slums of each fanbase.
I don't have much desire to go to any more games there. Being around 100,000 peaceful Iowa fans still makes me want to puke.