I stayed here for 9 nights and mostly had a good experience. The location alone can’t be beat. It’s between the Chuo (Okubo Station) and Yamanote lines (Shin Okubo Station) which makes a lot of Tokyo easily accessible and quick to reach. Main area of Shinjuku is walkable within 15 minutes.
Also right in Korea town which has so many great food options if you’re into that.
The room itself is a small apartment which was more than comfortable for 2 people (3 would probably be okay too). Beds were comfortable, and it was nice to be able to do laundry in the room
Cons: Slightly lacking in amenities like pots and pans, toilet paper, towels, garbage bags, etc., but extras were available upon request. Also could have been cleaned a bit more thoroughly.
Overall, I would stay here again.