The apartment is very close to Nishi-Ogikubo Station, which is a great jumping-off point for any of your travels around Tokyo. Upon confirming our reservation, our host Clyde sent us very thorough instructions for finding the apartment using Nishi-Ogikubo Station and the attached supermarket Seiyu as waypoints, and it couldn't have been easier to find.
The apartment itself is perfect for a couple, but it has an additional futon, blankets and pillows in the closet if you need to sleep a couple more people. We like to have a blanket a piece ourselves, so we contacted Clyde to get covers for an extra comforter, and he was very quick to respond and run them downstairs to us (he lives on site).
Lots of great food and convenience store choices are nearby if you need a quick bite before -- or after -- running around the city. The neighborhood is very quiet compared to others in Tokyo. The train can be a bit noisy, but that just comes with the territory. Also, the lights from the train are bright at night, but the curtains in the room are great at blocking it out.
Overall, this is a great spot to use as a homebase for a Tokyo adventure. Highest recommendation!