Great host. Nice cozy place with classy feel. The best way to describe my experience: it is pretty much as advertised. Nothing exaggerated in the pictures and description. Host was also very responsive to provide any additional details, help, and guidance.
As described, the unit can be too cozy for 3 people for both sleeping and moving, especially if you have a lot of bags in. One other thing that might be amiss here is to note that there is no elevator. So if you have very heavy luggage, especially more than a few, you may want to be prepared to lift them up 2 flights of narrow stairs. It would obviously also be tough if you have any condition challenging you from getting up/down the stairs.
Other than that, I was very very satisfied. Everything worked. All amenities were there. Check-in instructions were clear. Great area - some nice food just less than 5 minutes walking from the apartment, a lot more food beyond that (I like eating), walking distance to the major Shinjuku station, shopping centers, department stores, etc. The apartment itself is not exactly in the middle of a crowded area, but rather in a quiet and nice small neighborhood. As such, the location was just perfect!