First, the location is excellent. It's >5 minutes walking from Okubo Station, which is only 1 station over from Shinjuku. Very close to the Okubo shotengai as well, where you find a bunch of konbini, restaurants, supermarkets, drugstores etc. Also close to Shin-Okubo Station and Korea town.
Second, very responsive hosts. Both Henna and Big House would answer my messages within minutes. I stayed in their place for a month. Before and during my 1st week there I bombarded them with questions and they patiently answered each one. They also sent staff to check on the aircon after I asked.
Third, the unit I was staying at was very clean. The bathroom floor had some dark marks on it. But bathroom slippers were provided; I always used them and it was fine. The apartment building itself was filthy and unkempt when I arrived, but on the 3rd week it was all clean and fixed.
Overall, I'd recommend this place for singles and couples who want an affordable & strategic place to stay.