We enjoyed our stay in Shin-okubo. It's a great location and easy to walk to Shinjuku, but note that this area gets very busy on the weekends with people lining the streets around the station and main area, so it can be tricky to navigate with luggage. The apartment is pretty small (as to be expected) with a comfy bed. Not sure about using the sofa bed for extra person as not much floor space. The cleaning fee seemed a bit much (AU$50 for one night) as there were a few small cleaning issues when we stayed. Overall it was fine and communication was clear and efficient. The host left us some snacks which was a nice touch.