As a solo traveler, I stayed at the Shasha Guest House for nine nights total, and there was nothing to complain about the place.
The best thing about the guest house was the location. I could find everything I needed within ~500m and it was very close to Sinnonhyun stn and Gangnam Stn.
Also the owners were nice and helpful. They replied quickly to my inquiries during the stay, and they were always there to help. I appreciated their kindness and I would love to stay there again when I visit Korea again later.
I highly recommend this hotel for solo travelers who are planning a long trip to Seoul. The room is tiny but cozy enough to take rest at the end of the day.