We had a great time staying in Ohkubo's place.
The location is good - just a five minute walk from Shin-Ōkubo station on the Yamonote line, which connects you to the nightlife of Shinjuku and Shibuya in less than 10 minutes, and the rest of central Tokyo within 30 minutes.
The apartment was clean and cosy. Fairly small, but by Tokyo standards it's fine, especially if you're just looking for a quiet base to get some sleep and spending most of your time out exploring the city.
I would definitely recommend staying here.