I went to UIUC for my undergrad, and the cities (Urbana and Champaign) are alright. They have some good places to eat and drink, nothing spectacular but definitely passable.
I don't know where you come from (California?), but Illinois gets all four seasons. This winter has been exceptionally snowy and cold, with many days with highs in the single digits. Typically the highs are around freezing. The summers, if you'll be spending them here, are fairly hot and humid. Spring and fall tend to be short with long summers and winters. I know a grad student who came to UIUC from San Diego and the winter was a real adjustment for him. He had to go out and buy an actual winter coat for the first time.