I had a short, but very pleasant stay at Ohkubo's apartment. Personally, I wasn't too crazy about the neighborhood, but that's just my opinion. It was extremely close to the nearest train station, one stop away from Shinjuku. The apartment itself was very clean and pretty large for Japanese standards. The building was quiet and felt very safe.
Overall, if given the opportunity to stay there again, I wouldn't hesitate. I am definitely 100% satisfied.