My friend and I had a lovely stay at Konstantin's place. It's located in a lovely, quiet residential area and the house is very clean and tidy and has a great atmosphere. The room itself is very spacious and we loved it looks out over the garden.
Konstantin was very helpful and would let us check in early because our train arrived in the early afternoon. We really appreciated that!
The only thing I might say is that, although the location is lovely, it's less connected to train staions than described in the ad. Herne Hill is not a 5 minute but more around 12 minute walk, and Brixton is not a 15 minute walk but a 25 minute walk (the P4 bus does take you to Brixton in 15 minutes though), which made travelling across London not as quick as I had expected.
Overall we had a great stay and I would recommend!