Expect a uni dorm room. This is what the 'boutique hotel' actually is. It's student accomodation (see the plaque outside the entrance) Be prepared for a wooden mattress, 1cm thick pillows, no sound insulation between rooms, and a cramped semi working shower.
If you are looking for a bargain stay or a boozy weekend, then this place is great. If you want to have a comfortable weekend in Edinburgh with a loved one where you can get a good night's sleep, avoid this one.