The hotel NOT soundproof
First the pros:
The room was very clean and the cleaning staff friendly and helpful when we met them in the halls. 
The price was reasonable, and there was free parking.
The Giordano's down the street was a fun place to try Chicago deep dish pizza.
The cons:
When we checked in the person at the front desk was flustered and grumpy. There was no mention of being a Priority Club member, nor did there seem to be any benefit (other than points).
You can certainly hear the planes at the nearby airport taking off and landing. They don't go all night so that didn't really bother us, but it's not what I expect from an airport hotel.
The walls are thin - we could hear people talking and the bed creaking in the next room, as well as everyone who went by in the hallway. The toilets sound exactly like they do on an airplane, so yes, we could hear every time one of our neighbors flushed.
The worst experience we had was when a bus of young adults pulled up at 2 am and we could hear all the laughing and swearing going on for the next half hour as they hung around the front door smoking. I finally called down to the front desk and she said she would get security and the local police to deal with it. It quieted down about 10 minutes later. 
I would not recommend this hotel - there are many others in the same hotel complex, hopefully you would have better luck with one of them.