Just came back from a weekend at the Congress when in Chicago for Lolla 2013. It was a very last-minute booking and I was rather apprehensive after having read some reviews here but I think it is easy to exaggerate the hotel's obvious shortcomings. The hotel is a very decent pied-a-terre because location is excellent (short walk to Grant Park and Art Institute), well-connected for taking the metro (including direct train to O'Hare) and decent value for the area. The flipside is that this is not a glamorous or particularly pleasant hotel to spend a lot of time in, so if that's what you are looking for, you will be well disappointed: hotel is in serious need of renovation, everything about it looks old and worn out (but generally clean) and the in house facilities are basic. My room (on top floor) was also noisy and I could hear the train early in the morning.
Bottom line: this is not for your honeymoon or a romanic escape. But if looking for a basic room to sleep for a few hours while out in town, for the right price, I would certainly consider it again. More