My entire family and parents (6 total; parents, husband and wife and two children) stayed at Anna's apartment and it was fantastic.
The apartment is located in the Queens Park area. It's a little outside of the London core which we were looking for. The area has some excellent restaurants, grocery stores and some fun parks. Additionally, the Queens Park underground is a block from the apartment which provides quick and easy access to the tourist areas.
The apartment has 3 distinct rooms, a bathroom and a kitchen. It is very clean and accessible. The wifi was strong (I was able to stream MLB games).
The only downsides are the walls are thin and the mattresses are not terribly plush although it didn't really cause us any issues.
Anna is a wonderful host. She was very easy to reach and quick to respond. I would highly recommend Anna's place.