The good:
Nice home owned by a lovely family in one of London's poshest neighborhoods. Great communication with the hosts who even provided a regular cleaning service to take out the trash, clean the rooms, and do the dishes.
The not-so-good:
House is extremely cramped by North American or Australian standards. Stretch out two arms and you'll hit two walls. We tried to fit three families of four, four a total of twelve people. We made it work, but it wasn't easy. Expect to climb a lot of stairs, as there are five stories between the basement where the washing machine is located and the top floor--where we were sleeping. The dryer doesn't fully dry clothes. The basement bedrooms are rather claustrophobic and don't have proper air circulation. The family has left their clothing, family pictures, and other personal items out and about. Some people may find this charming, but it was a bit odd for us.
Verdict:
If you have eight to ten people in your group and want an authentic experience in a historic house in a great neighborhood--and don't mind some funky quirks--this could be a good choice.