It will be difficult to get a good sleep here. As other visitors have pointed out, the walls are paper-thin. You can hear the responses of your neighbor’s conversations over the phone. There are six units upstairs so chances are high you won’t be the only one there during your stay. During my stay, someone upstairs was running around past midnight. The bathroom is quite small even for Japan’s standards.
The location is great, direct subway to HND is available. Easy to walk to Tokyo tower, the unit can sleep three but there isn’t enough floor space to open three suitcases. It’s good for younger people traveling on a budget with friends but if your budget isn’t quite as tight I would look elsewhere.