I Go Hotel Tokyo is in an excellent location, situated in Koreatown close to both the JR Line Shin-Okubo station and the Metro Higashi-Shinjuku station. It is about 15 minutes walking from Shinjuku station. There are tons of Korean restaurants and standard Japanese cafes within a five minute walk, as well as a sento.
The hotel itself is clean and modern. I didn't have any problems using the keypad entry system. The rooms are standard size for Japan, although small by Western standards. My room had plenty of sunlight and a good heater, as well a hair dryer and electric kettle.
For a long stay, the hotel has two washers available on the third floor balcony. I didn't have any problems using the washers. There was limited space to hang clothing up to dry, but it worked out.
Airi was very responsive throughout the stay. We each texted in our native languages, and AirBnB's translation worked well. The hotel doesn't have a front desk, but when I needed a towel it was quickly dropped off.