I stayed five days and found it to be a comfortable flat in a great location. It is at the end of a shotengai shopping district by a train station just one stop from Shinjuku, so it is fabulously convenient and also feels like living in Tokyo.
Communication was fantastic. I contacted Pqd twice—once to get the access code early, prior to boarding a flight, and once because I'd locked myself out—and was able to get immediate help.
The room was clean and had everything (except an iron) that I needed. I thought the bed and TV was too big for the room, but that may be a personal preference.
It was quiet. There is some sound from intermittent traffic in the street, but I could not hear any of the neighbors except when they were on the stairs.