The good:
Location is fantastic! Lots of nice, small shops in the area and a very short walk to the Yamanote line, which will get you anywhere in Tokyo. The area itself is not too busy and has very few tourists. If you are looking for a convenient location that reflects how the average Japanese person live, this is a great place.
Has a sizeable desk.
The host is extremely responsive, but does not speak much English. This didn't cause any issues with our communication.
The not so good:
The apartment is not the newest nor the cleanest, but I wouldn't call it old or dirty. It also gets pretty cold in the winter and there is only one source of heat in the apartment (in the bedroom). It's only really powerful enough for the bedroom and living room, so the kitchen and bathroom are pretty cold.
Water takes a while to heat up (both bath and kitchen).
Could use more towels -- there was only two sets, which wasn't really enough for two people staying there for a week.
Overall:
The place is a great value in terms of convenience to the train. I would recommend it if you plan to be out of the apartment a lot and only use the place to sleep.