Communication with Martin was quick, friendly and efficient. We sadly did not meet him as he was out of town for the weekend, but every impression was a positive one. About the apartment itself it's difficult to add to the other reviews here. The location is excellent, with both the old town and a supermarket at walking distance, and on the inside it's as least as pretty as the pictures show. It felt a little like entering a time capsule, but with a few modern luxuries like a dishwasher and a vacuum hood. Something that pleasantly surprised us was the atmosphere in the apartment. Despite temperatures over 30 degrees outside, the apartment was never too warm or stuffy. And we didn't even need to use the aircon in the bedroom, opening the windows twice a day was sufficient.
Bottom line, we can only recommend staying here if you plan to visit Prague. The experience here was great and the price is more than reasonable.