Taxes in IL are pretty awful. Personal income tax is 5.5% right now (recently raised from 3%). Property tax is high. Sales tax is high (6.25% state plus local taxes all in upwards of 9% in some places). The state government is operating in huge deficit. A few years ago (and maybe now) they couldn't pay their bills. They were issuing IOUs instead.

These are things that you should consider before accepting the job. You really don't want to show up and find out that you are worse off.