Yuka's house is just like the pictures: Muji equipped, and not that big but super ok for 2 people. The bed is comfortable, and the bathroom convenient. It has a big balcony which makes it very bright. It's in the 7th floor of a building (there' an elevator, don't worry for the baggage) facing a sort of highway, so it can be a bit noisey if you keep windows open - don't worry, the room won't be hot as there's a fully working AC system. Also, the apartment has a washing machine, very silent and useful, fridge and microwave (we personally never used it and always ate outside). The area is ok, we had some issue to find a place for a breakfast at first, but then discovered a good place just outside the Hatagaya station (Le Repas), where you can find fresh baked salted and sweet stuff, both local and international and a good coffee. There are places to eat (we personally never tried them but Yuka provides a list of places in the area) and many 24h convenience stores. If you're a walker, the area can be at walking distance from Shibuya (30-40 minutes), many times we ate in Shibuya and then came back home by feet to see some new places - the area is really safe and nice to walk in it.
The self check in is really simple and fully explained in the infos provided. Yuka was present for every question we had, the wi-fi was maybe a bit slow but still ok for every day usage and directions. The area is served by a metro station nearby (Hatagaya) which is easily connected with the major spots.
I would recommend this place to everyone, and will definitely look for it next time I'm in Tokyo!