We (4 adults) were mostly quite happy with the apartment. It was clean and quiet, and in our opinion in a good location, only a few minutes walk from the tube station. The biggest problem was the sofa bed - it's NOT suitable for sleeping! 3 nights on that thing was really quite horrible. At least there should be an extra mattress for the sofa, or preferably the sofa should be changed for a one that's more suitable for sleeping, or change the apartment description to "2 persons only".
I didn't personally sleep on the proper bed in the bedroom, but I didn't hear any complaints from the others, so I guess that was all right :)