Great location and quaint apartment very close to the old town. Petra is a wonderful host and gave great recommendations for food, things to do etc.
There are some water stains on the ceiling and walls, however they were dry to the touch and didn't smell so they didn't bother us. There might be a neighbor who smokes because we noticed a smell coming through the open windows.
Also note that the ladder to get up to the loft is pretty steep so if you have trouble getting up ladders or are afraid of heights I wouldn't recommend sleeping in the loft bed.
Overall this is a great value apartment and a good place to stay for a few nights in Prague.