The host is very friendly and helpful. Very easy to communicate and they also stay in the neighbourhood. They allowed us to check-in earlier and offered to store our luggage after chek out.
We were travelling in a group of 4 adults. The room is very nice and suit to group travellers like us (mind the compact style of Japanese city housing). It has one separate bedroom that can fit 3 beds, dining/living area for additional 1-2 beds, workable laundry area and separate bathroom and toilet. The host equip the room with almost perfect amenities similar like a hotel (even more :) because of the cooking facilities etc), but we didn't cook.
The only cons is the steep stairs going up to our room in the second floor, but it was ok for us :), just be extra careful peeps.
The location is great as it is within few minutes walk (very close) from the JR Koenji station, which is 4-5 stops away from the shinjuku station. Lots of local restaurants and shops around but surprisingly not noisy during the evening/night. The area is also safe.
I would highly recommend the room.