Wehad a wonderful time at Choco's apartment! It's just 4 minutes from Koenji station by foot, it's very small but comfy (I'd not recommend it to big/overweight guests) and it was veeery clean :)
The neighborhood is quite and welcoming, there are a lot of combinis, 24h shops, laundry and restaurants in the area and you're literally 2 stops away from Shinjuku main station (by Chuo rapid line).
Great value from a small place, and I'd definitely recommend it to everyone visiting Tokyo!