The apartment was exactly as pictured and perfectly laid out for our family of four (including an 8 year old and a 5 year old). It was clean, nicely decorated, and had everything we needed - we were especially glad to be able to use the washer and dryer. We happened to be in London during a heat wave in June, and some rooms the apartment were a bit warm without AC, but every room had fans, which helped keep air circulating; the windows could be opened and the shades worked well.
The location was great - in a nice part of South Kensington, close to many shops, cafes, and museums, as well as the tube station. The Waitrose market around the block was great for all of our grocery needs.
The only snag we encountered was with check-in, which had been confirmed for 3 pm. The key was to be picked up from a cafe conveniently located just around the corner from the apartment. However, on arrival at 3:15, the security code provided was invalid. The contact I spoke with on the phone said they would look into the issue and call back in about 15 minutes. We ended up waiting on the street (fortunately the area had several cafes where we could sit) for about 45 minutes with our luggage and children. At 4 pm a new working code was provided. No explanation was given for the delay/nonfunctioning code. Apart from those 45 minutes without word, communication with the agency was easy and responses were quick.