The apartment is stylish, clean and cozy, and came with lots of nice little bonuses like cooking utensils and a pocket WiFi (if you are not planning to leave Tokyo, you can save yourself the substantial cost of buying a data-only SIM and safely rely on the pocket WiFi for your outdoor mobile data needs).
The location is very convenient for getting to Shibuya via the DT Line, but getting to Shinjuku requires changing to a different (JR) Metro network, which more or less doubles your transportation cost, if you plan to go there regularly during your stay.
Finally Kumina is a friendly and professional host, though there (I presume) is nobody physically present at the apartment units if you prefer somewhere with a local host to show you around. That said, he did reply to my inquiries promptly.