This flat is lovely and has everything you need for a comfortable stay. I was alone, so it felt like a much larger and nicer hotel room than the nearby options in the same price range. It is perfect for a couple at the very most. I can't imagine four people would be comfortable there. As mentioned in the description, this place has no elevator, and the stairs are pretty narrow, but I brought my suitcase up and down without any problem.
The location is very central, near major attractions, and conveniently located steps from my office. I would definitely book this place again if I return to London.