The house is absolutely beautiful and very spacious, set over 4 floors. All the bedrooms were spotlessly clean and the beds were well sized. The kitchen/dining room/living room area is large enough to accommodate everyone and has a nice balcony to sit out with a coffee. Other floors have a balcony area too, which contains space to hang washing if needed.
All appliances, lights, internet, air con and washer-drier work great, though you may need to look up on youtube for a guide to the translation of the interface (easy enough). There's a 100 yen store within 2 minutes walk of the house if you need any extra pillows or random items, and several 24 hour stores for food and drink. It's well situated and easy to get transport into central Tokyo.
The only issue is going to be finding the place initially as the link from the main page puts it in a wrong location. Instead, type the address itself into google maps. The house is roughly between 2 stations (Nakano Sakaue and Nishi Shinjuku Gochome) which are on lines that can take you to the main Shinjuku station. Leaving Nakano Sakaue station is easiest to find the place as it is 1 straight road there.
Wouldn't hesitate to recommend the place and would use it again myself in future.