The flat is really great ! It is very very very well located, just over the Bond street station in an English style building (there is an entrance for the station next to the door and you can reach Oxford street in just 5 seconds). We were 3 but you can easily go with 4-5 people in the flat (4 single beds and a couch). There is enough towels, blanket and pillows for everyone. There is a WiFi network for people who need it.
The owner of the flat is always ready to answer all of your questions and it is possible to make arrangement (we get he keys of the flat in a safe box because we arrived around 8-9pm in London, out of the opening hours).
Just a little thing, the windows are quite thin and during the night, you can sometimes hear some noise. But nothing to be afraid of.