After 3 MONTHS of actually living in Yoko's place, I'd really recommend this place to all my friends visiting Tokyo, especially if it's a couple on vacation, or a mid-long term business trip.
I'm from Tokyo originally, and I say the location and the neighborhood of Yoko's place is just the BEST - Yoyogi has a unique mixture of local authenticity and openness to diversity. The people are very friendly and open, yet somewhat classy, also stylish. During our stay, we got to know many nice "masters" from the neighborhood bars, cafes and restaurants -- they were all very welcoming and friendly to the English speaking newcomers like us, remembered us, greeted us, and made us feel like we are part of the community.
Another highlight of Yoko's place is its proximity to the Yoyogi park. It's basically right in front of the building - 3 mins walk to the entrance, but you can see the woods from the bedroom window. It's a beautiful park filled with tall woods, it has a pony park, a dog run, a boardwalk on the water, a big square for festivals in times, rose gardens and grass fields, also adjacent to the Meiji Shrine. From Yoko's house, Shibuya, Shinjuku, or Harajuku can be all accessed by just a 20-30 min walk through this park. (or a 5 min cab ride..)
The building of the apartment itself is located in between a road with a highway exit and a small railway, but it didnt really bother us. I actually liked this tram-like small train runninng in the neighborhood. It gives some local atmosphere.
All in all, we are very thankful that we found this place - especially under this worldwide covid situation. For us, it meant (still does mean) flight cancellation & months-long extension of our stay in Japan unplanned. The room was spacious enough for a couple to stay home + remote working for months peacefully, has unlimited WIFI, everything we needed to turn this months of worldwide uncertainty into a comfortable "workation" in central Tokyo.