Overall, Take and Yayoi's apartment is in a great location. The Takadanobaba train is a very easy four- to five-minute walk, and for newcomers to Japan, this station is a very good way to learn how Japan’s massive rail system works.
There are plenty of eateries and shops, including a delicious Vie De France bakery in Big Box, which offers lots of budget-friendly breakfast options and delicious coffee.
If arriving via taxi, the location is a little tucked away. (If you do use taxi, which isn't advised, and is very expensive in Japan, download the JapanTaxi app ahead of time.) As others have said, there are stairs and no elevator. But the stairs are very manageable.
The apartment is compact, clean and comfortable, with many amenities, towels and linens. That said, the unit is small, and as two adults, we found it hard to imagine it accommodating seven guests.
Overall, a very convenient location.
Take and Yoshi provide quick responses to our questions before and during our stay.
If you are not accustomed to traveling in Japan, know that there are strict rules regarding trash. There are few trash receptacles available, and you will need to keep your trash bagged in the apartment until the end of your stay. This was not a problem for us.