We spent 6 days at the Sumner during January 2013. Booking the hotel on line was uneventful, and a room of the quality that we expected was provided. The rooms were comfortable, quiet and well appointed with comfortable beds and a bathroom with a good shower with good water pressure. The room was somewhat warm, but no more so than any other place in London during winter. The breakfasts were good with a wide range of food and helpful attentive staff. There is limited room service.
One of the best features of this hotel is the location: close to Marble Arch tube station and Oxford Street and 2 good coffee shops (use Beanhunter app), and many good restaurants of varying prices and a 10 minute walk to Paddington Station.