Casey sends you very clear instructions on how to get to his house from both airports, which trains to catch and how much each cost.
The room is naturally bright with a really comfortable bed and memory foam pillows. We had great sleeps during our 4 nights. The space is big enough for 2 people and your suitcases. They leave a small USB charger for phones or other devices.
There is a pocket wifi which is very very handy when walking about so you always are connected to the internet. (It seems to work better when out and about rather than in the actual apartment. Some days it would be fine others it would drop in and out. Casey responded immediately after having some initial problems with the pocket wifi.
The laundry is great if your staying several days.
The location of the apartment is good, less than a min walk to the Nishi- shinjuku station. 1min to a seven eleven which we found that we would be at every morning before we headed out and every night before we get home. You can walk to Shinjuku area as we did on our first night we arrived. Places like Golden Gai etc. may take 20mins or so.
Overall me and my partner had a good stay, there are many places like this in Tokyo which are the same size (some smaller/even hotels). I would recommend it as it’s decent value for money.