I really enjoyed my stay in this flat. It's very well located, a few minutes from Koenji station and only a minute from lots of shops, bars and restaurants. Despite that it's mostly quiet as it's down a narrow side-street with no traffic.
The flat is compact and simple but more than adequate for a short stay. The only heating is from an air conditioner but as it's a small space it doesn't take long to warm up. There's no curtain on one window so you might want to pack an eye-mask.
Takashi-san and Shiho-san were really welcoming, very friendly and gave me lots of advice on how to find the place and where to go for food, though I ended up eating some delicious pizza in their restaurant downstairs!
All in all, it's amazingly good value for a comfortable stay in one of the most exciting neighourhoods in Tokyo. Recommended!