I had the pleasure of being the apartment's first visitor after Mats moved out. The apartment is great, very spacious by Amsterdam standards, with extremely high ceilings, large windows, and a very nice balcony. It's not right "smack in Dam Square", but is within a short walk from many attractions, and has a beautiful canal, draw bridge, and restaurants next door.
Mats was great, providing information and instructions ahead of time, coming to the apartment to explain everything when the rental started, and texting daily to check if everything was okay and if I needed anything. It was as if the apartment came with a personal concierge.