The location and appartment are perfect. It is a very good size for 3 persons. It is in a quiet street, but you can just walk up to busy Shinjuku (or take on stop at the Yamanote line). Breakfast downstairs in Domo café was also nice. And we were very happy with the airco, since it was 35 degrees Celsius.
The only comment I have was that the beds were really hard. This is personal though, because some people like this. But we would definitely recommend this appartment.