We stayed at Jeff's place for the last leg of our trip in Tokyo (3 nights / 4 days). Wish we had found out about this place sooner! It was a wonderful stay and experience. Jeff and Kiki were always quick to respond, and very helpful with tips for the stay.
Our apt was clean, and includes a spacious bathtub and shower (which were greatly appreciated given the amount of walking done every day), as well as a clothes washer. Very modernly designed, and came with all necessary amenities including extras like slippers.
The motel itself is located in a quieter residential neighbourhood, but within a 10-15 minute walk from Shinjuku station, and also a VERY close walk to JR Okubo and Shin-Okubo, which should allow you to access most, if not all, tourist hubs. The instructions provided make the motel very easy to find.
It's really clear that both Jeff and Kiki care about their guests, and having their guests get the best experience. Would definitely recommend staying here - just make sure you can carry your luggage (or request a first-floor apt) as there is no elevator.