Hi fellow guests, the 'Shinjuku Sharehouse' is just as great as the (100s of positive) reviews are claiming. With the subway so closeby, you can reach all the touristic places within the hour (From Shibuya, through Harajuku, to Shinjuku's appartment is actually only 5km appart, this is walking distance). Min is a real dedicated Airbnb host, so he provides all the info you need. During my 4 night stay, he was there every morning and few nights as well. As an artist, he made some paintings while I was there and even had us participate. Min also took us out for dinner (I missed 1 night).
The other guests during my stay were so much fun and added so much more to the experience as well. I went alone but returned with many new friends.
The private room was just perfect for me, tatami floor, and more than enough space for 1 person (is probably meant for 3).
The appartment I was in basically has the entrance, common livingroom with kitchen, bathroom and toilet. From inside there you have rooms if you go up or down the stairs (3floor appartments). I think Min owns all the top floors, including the roof, and for the daredevils, you can climb onto the roof of a shack on this roof, for a perfect 360° Shinjuku view.
Don't take my word for how great this place is, you can take it from the other 100s of reviews =)

PS: Shinjuku's best sushi place (or #2 restaurant of all of Shinjuku, out of 5500+ restos) according to TripAdvisor is just 15m away from downstairs the appartment.