We stayed in the Kew House during three nights in May 2008.
Kew House is probably not the cheapest bed and breakfast or guest house in Edinburgh, but it's worth the price: the rooms and dining room are very comfortable, clean and with a lot of light. The Kew House is very well situated in Edinburgh, at a walking distance of the center of the town (around 25 minutes), and there are buses passing in front of the house to go from and to the city center (about 10 minutes) and to the airport.
Breakfast was fantastic: a lot of hot and cold food on the menu, choice of different teas and coffee, fruits, traditional scottish breakfast (humm, haggis ;-))
Last but not least, Ian and Alan, the owners, are more than friendly and can give very good advices on places to go in Edinburgh: we have tried three different restaurants that they have recommended to us, and all three where of the highest quality without being expensive.
We would definitely come back to the Kew House in the future, and recommend it to our friends.