We stayed for one month at James and Cheryl's place and the flat exceeded our expectations. We knew it would be small from the photos and were a bit wary to stay for so long (but it was a great deal) - however, it ended up being bigger than it appeared in the photos, and even with the huge amount of luggage that we had from just having moved to London, we were very comfortable since there was so much storage space. Every square foot of this apartment has been utilized efficiently - it is an engineering marvel. Even the dishes are all the exact right size that the dishwasher can be loaded to max capacity. I cannot emphasize enough how well-thought-out this space is!
Everything was extremely clean and we found everything we needed at the apartment, including cable TV and streaming services. The kitchen was very well-equipped with plenty of counter space and good-quality appliances. The shower was large enough and had perfect temperature and water pressure settings. You can see outside during the day without the passersby seeing you because of a tint on the glass (but it still let in lots of natural light, plus there is a skylight). We were perfectly warm in October and the floors are heated in the winter.
As for location, it was definitely a bit far from the centre, but we had known it would be. The walk to Norbury train station was at least 20 minutes at a brisk walk. That being said, one of the only Lidls in the city is only a 15-minute walk, and it is uphill (meaning that you are going downhill once you are actually carrying groceries, so it really is a plus). Streatham Common is very picturesque and it is also a short walk from the house.
James and Cheryl were pleasant and considerate and helped us out with any questions we had.