I stayed at Mary's for the Step 2 CS exam (as she advertised, it's really close!), and I was very happy with my stay. The upstairs is undergoing some renovation, so there's a lot of stuff in the living room, but the other areas of the house- bedrooms, bathroom, and kitchen- are very clean and well-organized. Mary was also very accommodating when I had to leave a bag to pick up later even after I checked out, since I could not take luggage to the testing site. I would highly recommend to any other medical students taking the exam, or to anyone who's looking for a nice place to stay close to O'Hare.