We found the location very convenient for Robot Restaurant and Tokyo Mystery Circus. It is an easy walk to Shinjuku Station; however, it is a very large station so you'll want to pay attention to which entrance/exit you use.
The space was clean and exactly as pictured. We were never bothered by noise. As shown in the floor plan, the toilet room, shower, and bedroom/living room are accessed from the front hallway area. We never bumped into our host, but he passes through the hallway when he leaves/comes home. The bedroom door and of course the toilet room door can be locked from the inside only. The folding door to the kitchenette and shower closes securely with magnets but cannot be locked.
We really liked having the extra living room space directly off of the bedroom. One side table drawer had a variety of area maps and guides, and another contained some dishes and utensils. There was ample closet space and the bed was comfortable. The only negative was that the sofa was quite low and difficult for us to get up from once we were seated. If you are older or have mobility issues, you might not be able to use the sofa comfortably.
Overall we were very happy with our stay.