Excellent place. Koenji is a lovely surburb and is perfectly positioned as a nice quiet place to retreat to after the craziness of Shinjuku/Shibuya.
it's only 15 min from the hotel to Shinjuku station (by train), which is really handy as Shinjuku connects to everything.
the room itself was small and cozy with everything you need to be comfortable.
the location it's in in dead quiet at night