The unit is located on the top floor, 4th floor. So if you have heavy luggage or rolling luggages you will have to carry them up four levels of stairs since there is no elevator. This wasn't a problem for us but I can see this as a problem for some.
The Japanese futon wasn't as comfortable as other Airbnb or Ryokans I've stayed at. It was too thin and the pillows were completely flat even when trying to fluff them up. I'm a back sleeper and even then it was hard falling asleep. Since it felt like I was just sleeping on the floor. Those who are side sleepers may want to reconsider their sleeping conditions. Everything else other than those was great.
The unit itself is located in a quiet residence and near a family mart and also next to a supermarket if you need to go grocery shopping. Couple minutes away from the station and couple station stops from Shinjuku.