Overall, we enjoyed our stay at Shinjuku-ku. The place is conveniently located near two JR stations, Ōkubo (Chūō-Sōbu Line) and Shin-Ōkubo (Yamanote Line). It was also very close to a Don Quijote, which was another benefit. Unfortunately, the neighborhood isn't the best with many abandoned buildings nearby.
We like that there was ac/heating in each of the rooms, and there were coat racks/closet rods (depending on the room). There were two showers (no tubs), which had many amenities, like toothpaste, shampoo, conditioner, face wash, etc.
Our biggest complaint was that the washer did not have a dryer function, even though it was listed as an amenity. During our investigation, we found that the washing machine filter was moldy and we ended up cleaning it in an attempt to debug the dryer function that did not exist. The host seemed apologetic (about the dryer), but nothing was done to remedy the situation. We ended up using the nearby coin laundry, Laundromat Futaba.