@IcedCapp Congrats on the offer! As an international student who came from a city very much like yours and never lived in a small town before moving to CU, I have to say I didn't really like living there. I found it quite boring, and the city didn't grow on me throughout the few years I spend there at all. To me, living in a place with a lot of cultural activities, which is nonexistent in CU, is very important. Also, I was in a social science department and CU is an extremely engineering oriented place, and there wasn't a lot of exciting activities for us. That being said, I did meet a lot of people who enjoyed CU for different reasons.
Climate is very unpredictable in CU, and the winters are very rough. However, that really depends on the climate you are used to. In my city, below 0 C is rare, and it only snows 2-3 times in winters, so I found CU winters very hard to cope with. Other than the winters, summers are too hot, but the fall is very nice and it lasts long. Public transportation is really nice, if you choose your neighborhood wisely, you can actually rely on buses to go to class. I also really enjoyed the Amtrak rides to Chicago (which takes two and a half hours on average), and I went to the city for daily trips or for weekends frequently.
Political atmosphere is an important criteria for me as well, and like climate, what you are already used to matters a lot. It is not nonexistent, but as someone who came from a university with an active political life, I found CU and the campus quite disappointing. Undergrad involvement in political activities is low, and that makes a difference.
You hear about security a lot before going there, but I didn't experience anything bad. I lived in a few neighborhoods in Champaign, and I love the West Champaign area outside the campus best (south/west from Champaign Public Library, which is also a good study spot). It is a quiet area mostly occupied by grad students. Also, if you contact the tenant union, they send you a list of all the landlords with complaint records (https://tenantunion.illinois.edu/lookinghousing.asp) which I found very helpful. Overall, CU isn't an expensive place, but housing can be a problem. I recommend you to stay away on-campus apartments in Champaign, they tend to be small and overpriced.
I will be happy to answer if you have more questions!