Excellent location within walking distance of many museums, we enjoyed 4 super days. Marc was a very friendly host, prompt in answering all questions, and able to provide good advice of the local area. He was also very flexible when we arrived slightly early.
While the apartment is on the small side for 5 people, we knew this before we booked and for four days was absolutely no problem. The flat itself was clean, quiet and included everything we needed.
For information, we had our own car with us and parked this in the Cadogan Place NCP (only 12 minutes by foot), booking in advance for a reasonable price. It involves a bit more administration, especially if you need to pay the congestion charge, but we needed this flexibility as we had combined other visits in the UK.