G-stays was exactly what we were looking for and David was a great host.
The location is great for access to Shinjuku and there's plenty of transport links to get around. If arriving with bags/cases I recommend planning your route to the Higashi-Shinjuku station as it is super close and saves a lot of walking with bags/cases.
The room size is standard for Tokyo (which is smaller than a western average), we didn't have any issues here and the room had everything we needed. You really get the feel of staying in a Tokyo style apartment, even though you're sure to spend most of your time out enjoying Tokyo.
Overall a great spot and accommodation, especially at its price point. We would certainly consider staying again if we were ever back in Tokyo/Shinjuku.