Sam's place was very good for our need ( i.e explore Washington DC highlights).
It's about 20 min by foot from the White House and very close to a subway station. There is a supermarket and quite a few restaurants nearby.
As others have stated, the place is larger than it looks in the pictures. It's nicely decorated and well equipped.
We were a bit worried about parking as there was not private parking, and we ended finding the perfect spot, literally in front of the door - and for free !
Sam was very helpful in his communications.
There is a hospital very close and we hear ambulances a couple times in the middle of the night -> if you are a light sleeper, bring some ear plugs.