I had a pleasant stay.
The apartment was perfect for two, simple and clean, with a small corner of kitchen.
It took me 15mins walk to Shinjuku city centre, the distance was acceptable. However, the wifi in the house was disappointing, comparatively slow. The residential area is quiet and peaceful, however, the house wall was thin so I could hear the conversation from next door.
The host is very responsive, provided detail direction map and check in information to me as soon as I confirmed my booking.